diff --git a/src/activation.cpp b/src/activation.cpp
index cab9acd..ca8c7df 100644
--- a/src/activation.cpp
+++ b/src/activation.cpp
@@ -127,9 +127,11 @@
     auto assocs = associations();
     assocs.emplace_back(ACTIVATION_FWD_ASSOCIATION, ACTIVATION_REV_ASSOCIATION,
                         currentUpdatingPsu);
-    currentUpdatingPsu.clear();
     associations(assocs);
 
+    activationListener->onUpdateDone(versionId, currentUpdatingPsu);
+    currentUpdatingPsu.clear();
+
     psuQueue.pop();
     doUpdate(); // Update the next psu
 }
@@ -218,7 +220,6 @@
     storeImage();
     activationProgress->progress(100);
 
-    // TODO: delete the old software object
     deleteImageManagerObject();
 
     associationInterface->createActiveAssociation(objPath);
diff --git a/src/activation.hpp b/src/activation.hpp
index 669686e..3b03803 100644
--- a/src/activation.hpp
+++ b/src/activation.hpp
@@ -2,6 +2,7 @@
 
 #include "config.h"
 
+#include "activation_listener.hpp"
 #include "association_interface.hpp"
 #include "types.hpp"
 #include "version.hpp"
@@ -129,8 +130,9 @@
     Activation(sdbusplus::bus::bus& bus, const std::string& objPath,
                const std::string& versionId, const std::string& extVersion,
                Status activationStatus, const AssociationList& assocs,
+               const std::string& filePath,
                AssociationInterface* associationInterface,
-               const std::string& filePath) :
+               ActivationListener* activationListener) :
         ActivationInherit(bus, objPath.c_str(), true),
         bus(bus), objPath(objPath), versionId(versionId),
         systemdSignals(
@@ -140,7 +142,8 @@
                 sdbusRule::interface("org.freedesktop.systemd1.Manager"),
             std::bind(&Activation::unitStateChange, this,
                       std::placeholders::_1)),
-        associationInterface(associationInterface)
+        associationInterface(associationInterface),
+        activationListener(activationListener)
     {
         // Set Properties.
         extendedVersion(extVersion);
@@ -278,6 +281,9 @@
     /** @brief The AssociationInterface pointer */
     AssociationInterface* associationInterface;
 
+    /** @brief The activationListener pointer */
+    ActivationListener* activationListener;
+
     /** @brief The PSU manufacturer of the software */
     std::string manufacturer;
 
diff --git a/src/activation_listener.hpp b/src/activation_listener.hpp
new file mode 100644
index 0000000..5437232
--- /dev/null
+++ b/src/activation_listener.hpp
@@ -0,0 +1,17 @@
+#pragma once
+
+#include <string>
+
+class ActivationListener
+{
+  public:
+    virtual ~ActivationListener() = default;
+
+    /** @brief Notify a PSU is updated
+     *
+     * @param[in]  versionId - The versionId of the activation
+     * @param[in]  psuInventoryPath - The PSU inventory path that is updated
+     */
+    virtual void onUpdateDone(const std::string& versionId,
+                              const std::string& psuInventoryPath) = 0;
+};
diff --git a/src/item_updater.cpp b/src/item_updater.cpp
index acbc943..6d4e4c2 100644
--- a/src/item_updater.cpp
+++ b/src/item_updater.cpp
@@ -179,14 +179,29 @@
     }
 }
 
+void ItemUpdater::onUpdateDone(const std::string& versionId,
+                               const std::string& psuInventoryPath)
+{
+    // After update is done, remove old activation objects
+    for (auto it = activations.begin(); it != activations.end(); ++it)
+    {
+        if (it->second->getVersionId() != versionId &&
+            utils::isAssociated(psuInventoryPath, it->second->associations()))
+        {
+            removePsuObject(psuInventoryPath);
+            break;
+        }
+    }
+}
+
 std::unique_ptr<Activation> ItemUpdater::createActivationObject(
     const std::string& path, const std::string& versionId,
     const std::string& extVersion, Activation::Status activationStatus,
     const AssociationList& assocs, const std::string& filePath)
 {
     return std::make_unique<Activation>(bus, path, versionId, extVersion,
-                                        activationStatus, assocs, this,
-                                        filePath);
+                                        activationStatus, assocs, filePath,
+                                        this, this);
 }
 
 void ItemUpdater::createPsuObject(const std::string& psuInventoryPath,
diff --git a/src/item_updater.hpp b/src/item_updater.hpp
index b713454..c3da8f9 100644
--- a/src/item_updater.hpp
+++ b/src/item_updater.hpp
@@ -35,7 +35,9 @@
 /** @class ItemUpdater
  *  @brief Manages the activation of the PSU version items.
  */
-class ItemUpdater : public ItemUpdaterInherit, public AssociationInterface
+class ItemUpdater : public ItemUpdaterInherit,
+                    public AssociationInterface,
+                    public ActivationListener
 {
     friend class ::TestItemUpdater;
 
@@ -84,6 +86,14 @@
      */
     void removeAssociation(const std::string& path) override;
 
+    /** @brief Notify a PSU is updated
+     *
+     * @param[in]  versionId - The versionId of the activation
+     * @param[in]  psuInventoryPath - The PSU inventory path that is updated
+     */
+    void onUpdateDone(const std::string& versionId,
+                      const std::string& psuInventoryPath) override;
+
   private:
     /** @brief Callback function for Software.Version match.
      *  @details Creates an Activation D-Bus object.
diff --git a/test/mocked_activation_listener.hpp b/test/mocked_activation_listener.hpp
new file mode 100644
index 0000000..cbef46d
--- /dev/null
+++ b/test/mocked_activation_listener.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "activation_listener.hpp"
+
+#include <gmock/gmock.h>
+
+class MockedActivationListener : public ActivationListener
+{
+  public:
+    virtual ~MockedActivationListener() = default;
+
+    MOCK_METHOD2(onUpdateDone, void(const std::string& versionId,
+                                    const std::string& psuInventoryPath));
+};
diff --git a/test/test_activation.cpp b/test/test_activation.cpp
index 97efe79..a7ce542 100644
--- a/test/test_activation.cpp
+++ b/test/test_activation.cpp
@@ -1,4 +1,5 @@
 #include "activation.hpp"
+#include "mocked_activation_listener.hpp"
 #include "mocked_association_interface.hpp"
 #include "mocked_utils.hpp"
 
@@ -62,6 +63,7 @@
     sdbusplus::bus::bus mockedBus = sdbusplus::get_mocked_new(&sdbusMock);
     const utils::MockedUtils& mockedUtils;
     MockedAssociationInterface mockedAssociationInterface;
+    MockedActivationListener mockedActivationListener;
     std::unique_ptr<Activation> activation;
     std::string versionId = "abcdefgh";
     std::string extVersion = "manufacturer=TestManu,model=TestModel";
@@ -75,7 +77,7 @@
 {
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
 }
 
 TEST_F(TestActivation, ctorWithInvalidExtVersion)
@@ -83,7 +85,7 @@
     extVersion = "invalid text";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
 }
 
 TEST_F(TestActivation, getUpdateService)
@@ -96,7 +98,7 @@
 
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
 
     auto service = getUpdateService(psuInventoryPath);
     EXPECT_EQ(toCompare, service);
@@ -106,7 +108,7 @@
 {
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(
             Return(std::vector<std::string>({}))); // No PSU inventory
@@ -116,6 +118,7 @@
         .Times(0);
     EXPECT_CALL(mockedAssociationInterface, addFunctionalAssociation(dBusPath))
         .Times(0);
+    EXPECT_CALL(mockedActivationListener, onUpdateDone(_, _)).Times(0);
     EXPECT_EQ(Status::Failed, activation->activation());
 }
 
@@ -124,7 +127,7 @@
     constexpr auto psu0 = "/com/example/inventory/psu0";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(
             Return(std::vector<std::string>({psu0}))); // One PSU inventory
@@ -136,6 +139,9 @@
         .Times(1);
     EXPECT_CALL(mockedAssociationInterface, addFunctionalAssociation(dBusPath))
         .Times(1);
+    EXPECT_CALL(mockedActivationListener,
+                onUpdateDone(StrEq(versionId), StrEq(psu0)))
+        .Times(1);
     onUpdateDone();
     EXPECT_EQ(Status::Active, activation->activation());
 }
@@ -148,7 +154,7 @@
     constexpr auto psu3 = "/com/example/inventory/psu3";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(Return(
             std::vector<std::string>({psu0, psu1, psu2, psu3}))); // 4 PSUs
@@ -157,14 +163,23 @@
     EXPECT_EQ(Status::Activating, activation->activation());
     EXPECT_EQ(10, getProgress());
 
+    EXPECT_CALL(mockedActivationListener,
+                onUpdateDone(StrEq(versionId), StrEq(psu0)))
+        .Times(1);
     onUpdateDone();
     EXPECT_EQ(Status::Activating, activation->activation());
     EXPECT_EQ(30, getProgress());
 
+    EXPECT_CALL(mockedActivationListener,
+                onUpdateDone(StrEq(versionId), StrEq(psu1)))
+        .Times(1);
     onUpdateDone();
     EXPECT_EQ(Status::Activating, activation->activation());
     EXPECT_EQ(50, getProgress());
 
+    EXPECT_CALL(mockedActivationListener,
+                onUpdateDone(StrEq(versionId), StrEq(psu2)))
+        .Times(1);
     onUpdateDone();
     EXPECT_EQ(Status::Activating, activation->activation());
     EXPECT_EQ(70, getProgress());
@@ -174,6 +189,9 @@
     EXPECT_CALL(mockedAssociationInterface, addFunctionalAssociation(dBusPath))
         .Times(1);
 
+    EXPECT_CALL(mockedActivationListener,
+                onUpdateDone(StrEq(versionId), StrEq(psu3)))
+        .Times(1);
     onUpdateDone();
     EXPECT_EQ(Status::Active, activation->activation());
 }
@@ -186,7 +204,7 @@
     constexpr auto psu3 = "/com/example/inventory/psu3";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(Return(
             std::vector<std::string>({psu0, psu1, psu2, psu3}))); // 4 PSUs
@@ -195,6 +213,9 @@
     EXPECT_EQ(Status::Activating, activation->activation());
     EXPECT_EQ(10, getProgress());
 
+    EXPECT_CALL(mockedActivationListener,
+                onUpdateDone(StrEq(versionId), StrEq(psu0)))
+        .Times(1);
     onUpdateDone();
     EXPECT_EQ(Status::Activating, activation->activation());
     EXPECT_EQ(30, getProgress());
@@ -203,6 +224,7 @@
         .Times(0);
     EXPECT_CALL(mockedAssociationInterface, addFunctionalAssociation(dBusPath))
         .Times(0);
+    EXPECT_CALL(mockedActivationListener, onUpdateDone(_, _)).Times(0);
     onUpdateFailed();
     EXPECT_EQ(Status::Failed, activation->activation());
 }
@@ -212,7 +234,7 @@
     constexpr auto psu0 = "/com/example/inventory/psu0";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(
             Return(std::vector<std::string>({psu0}))); // One PSU inventory
@@ -229,7 +251,7 @@
     extVersion = "manufacturer=TestManu,model=DifferentModel";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(Return(std::vector<std::string>({psu0})));
     activation->requestedActivation(RequestedStatus::Active);
@@ -243,7 +265,7 @@
     extVersion = "manufacturer=DifferentManu,model=TestModel";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(Return(std::vector<std::string>({psu0})));
     activation->requestedActivation(RequestedStatus::Active);
@@ -260,7 +282,7 @@
     constexpr auto psu0 = "/com/example/inventory/psu0";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(
             Return(std::vector<std::string>({psu0}))); // One PSU inventory
@@ -287,7 +309,7 @@
             Return(any(PropertyType(std::string("DifferentModel")))));
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(Return(
             std::vector<std::string>({psu0, psu1, psu2, psu3}))); // 4 PSUs
@@ -325,7 +347,7 @@
     constexpr auto psu0 = "/com/example/inventory/psu0";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
 
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(
@@ -348,7 +370,7 @@
     constexpr auto psu0 = "/com/example/inventory/psu0";
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
 
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(
@@ -369,7 +391,7 @@
     status = Status::Active; // Typically, a running PSU software is associated
     activation = std::make_unique<Activation>(
         mockedBus, dBusPath, versionId, extVersion, status, associations,
-        &mockedAssociationInterface, filePath);
+        filePath, &mockedAssociationInterface, &mockedActivationListener);
 
     ON_CALL(mockedUtils, getPSUInventoryPath(_))
         .WillByDefault(
diff --git a/test/test_item_updater.cpp b/test/test_item_updater.cpp
index b4ecafc..cbea53c 100644
--- a/test/test_item_updater.cpp
+++ b/test/test_item_updater.cpp
@@ -490,3 +490,111 @@
         .Times(1);
     scanDirectory("./psu-images-valid-version0");
 }
+
+TEST_F(TestItemUpdater, OnUpdateDoneOnTwoPSUsWithSameVersion)
+{
+    // Simulate there are two PSUs with same version, and updated to a new
+    // version
+    constexpr auto psu0 = "/com/example/inventory/psu0";
+    constexpr auto psu1 = "/com/example/inventory/psu1";
+    constexpr auto service = "com.example.Software.Psu";
+    auto version0 = std::string("version0");
+    auto version1 = std::string("version0");
+    auto objPath0 = getObjPath(version0);
+    auto objPath1 = getObjPath(version1);
+
+    EXPECT_CALL(mockedUtils, getPSUInventoryPath(_))
+        .WillOnce(Return(std::vector<std::string>({psu0, psu1})));
+    EXPECT_CALL(mockedUtils, getService(_, StrEq(psu0), _))
+        .WillOnce(Return(service));
+    EXPECT_CALL(mockedUtils, getService(_, StrEq(psu1), _))
+        .WillOnce(Return(service));
+    EXPECT_CALL(mockedUtils, getVersion(StrEq(psu0)))
+        .WillOnce(Return(std::string(version0)));
+    EXPECT_CALL(mockedUtils, getPropertyImpl(_, StrEq(service), StrEq(psu0), _,
+                                             StrEq(PRESENT)))
+        .WillOnce(Return(any(PropertyType(true)))); // present
+    EXPECT_CALL(mockedUtils, getVersion(StrEq(psu1)))
+        .WillOnce(Return(std::string(version1)));
+    EXPECT_CALL(mockedUtils, getPropertyImpl(_, StrEq(service), StrEq(psu1), _,
+                                             StrEq(PRESENT)))
+        .WillOnce(Return(any(PropertyType(true)))); // present
+
+    itemUpdater = std::make_unique<ItemUpdater>(mockedBus, dBusPath);
+
+    // Now there is one activation and it has two associations
+    auto& activations = GetActivations();
+    auto& activation = activations.find(version0)->second;
+    auto assocs = activation->associations();
+    EXPECT_EQ(2u, assocs.size());
+    EXPECT_EQ(psu0, std::get<2>(assocs[0]));
+    EXPECT_EQ(psu1, std::get<2>(assocs[1]));
+
+    EXPECT_CALL(mockedUtils, isAssociated(StrEq(psu0), _))
+        .WillOnce(Return(true));
+    itemUpdater->onUpdateDone("A new version", psu0);
+
+    // Now the activation should have one assoiation
+    assocs = activation->associations();
+    EXPECT_EQ(1u, assocs.size());
+    EXPECT_EQ(psu1, std::get<2>(assocs[0]));
+
+    EXPECT_CALL(mockedUtils, isAssociated(StrEq(psu1), _))
+        .WillOnce(Return(true));
+    itemUpdater->onUpdateDone("A new version", psu1);
+
+    // Now the activation shall be erased
+    EXPECT_EQ(0u, activations.size());
+}
+
+TEST_F(TestItemUpdater, OnUpdateDoneOnTwoPSUsWithDifferentVersion)
+{
+    // Simulate there are two PSUs with different version, and updated to a new
+    // version
+    constexpr auto psu0 = "/com/example/inventory/psu0";
+    constexpr auto psu1 = "/com/example/inventory/psu1";
+    constexpr auto service = "com.example.Software.Psu";
+    auto version0 = std::string("version0");
+    auto version1 = std::string("version1");
+    auto objPath0 = getObjPath(version0);
+    auto objPath1 = getObjPath(version1);
+
+    EXPECT_CALL(mockedUtils, getPSUInventoryPath(_))
+        .WillOnce(Return(std::vector<std::string>({psu0, psu1})));
+    EXPECT_CALL(mockedUtils, getService(_, StrEq(psu0), _))
+        .WillOnce(Return(service));
+    EXPECT_CALL(mockedUtils, getService(_, StrEq(psu1), _))
+        .WillOnce(Return(service));
+    EXPECT_CALL(mockedUtils, getVersion(StrEq(psu0)))
+        .WillOnce(Return(std::string(version0)));
+    EXPECT_CALL(mockedUtils, getPropertyImpl(_, StrEq(service), StrEq(psu0), _,
+                                             StrEq(PRESENT)))
+        .WillOnce(Return(any(PropertyType(true)))); // present
+    EXPECT_CALL(mockedUtils, getVersion(StrEq(psu1)))
+        .WillOnce(Return(std::string(version1)));
+    EXPECT_CALL(mockedUtils, getPropertyImpl(_, StrEq(service), StrEq(psu1), _,
+                                             StrEq(PRESENT)))
+        .WillOnce(Return(any(PropertyType(true)))); // present
+
+    itemUpdater = std::make_unique<ItemUpdater>(mockedBus, dBusPath);
+
+    // There are two activations and each with one association
+    const auto& activations = GetActivations();
+    EXPECT_EQ(2u, activations.size());
+
+    EXPECT_CALL(mockedUtils, isAssociated(StrEq(psu0), _))
+        .WillOnce(Return(true));
+    // After psu0 is done, only one activation should be left
+    itemUpdater->onUpdateDone("A new version", psu0);
+    EXPECT_EQ(1u, activations.size());
+    const auto& activation1 = activations.find(version1)->second;
+    const auto& assocs1 = activation1->associations();
+    EXPECT_EQ(1u, assocs1.size());
+    EXPECT_EQ(psu1, std::get<2>(assocs1[0]));
+
+    EXPECT_CALL(mockedUtils, isAssociated(StrEq(psu1), _))
+        .WillOnce(Return(true));
+    // After psu1 is done, no activation should be left
+    itemUpdater->onUpdateDone("A new version", psu1);
+    EXPECT_EQ(0u, activations.size());
+}