diff --git a/libs/server-sdk/src/data_components/memory_store/memory_store.cpp b/libs/server-sdk/src/data_components/memory_store/memory_store.cpp
index 95cac8748..c71acf08a 100644
--- a/libs/server-sdk/src/data_components/memory_store/memory_store.cpp
+++ b/libs/server-sdk/src/data_components/memory_store/memory_store.cpp
@@ -1,5 +1,7 @@
 #include "memory_store.hpp"
 
+#include <launchdarkly/detail/unreachable.hpp>
+
 namespace launchdarkly::server_side::data_components {
 
 std::shared_ptr<data_model::FlagDescriptor> MemoryStore::GetFlag(
@@ -82,4 +84,34 @@ bool MemoryStore::RemoveSegment(std::string const& key) {
     return segments_.erase(key) == 1;
 }
 
+void MemoryStore::Apply(data_model::FDv2ChangeSet changeSet) {
+    std::lock_guard lock{data_mutex_};
+
+    switch (changeSet.type) {
+        case data_model::FDv2ChangeSet::Type::kNone:
+            return;
+        case data_model::FDv2ChangeSet::Type::kPartial:
+            break;
+        case data_model::FDv2ChangeSet::Type::kFull:
+            initialized_ = true;
+            flags_.clear();
+            segments_.clear();
+            break;
+        default:
+            detail::unreachable();
+    }
+
+    for (auto& change : changeSet.changes) {
+        if (std::holds_alternative<data_model::FlagDescriptor>(change.object)) {
+            flags_[change.key] = std::make_shared<data_model::FlagDescriptor>(
+                std::move(std::get<data_model::FlagDescriptor>(change.object)));
+        } else if (std::holds_alternative<data_model::SegmentDescriptor>(
+                       change.object)) {
+            segments_[change.key] =
+                std::make_shared<data_model::SegmentDescriptor>(std::move(
+                    std::get<data_model::SegmentDescriptor>(change.object)));
+        }
+    }
+}
+
 }  // namespace launchdarkly::server_side::data_components
diff --git a/libs/server-sdk/src/data_components/memory_store/memory_store.hpp b/libs/server-sdk/src/data_components/memory_store/memory_store.hpp
index 93dfca485..e9a067881 100644
--- a/libs/server-sdk/src/data_components/memory_store/memory_store.hpp
+++ b/libs/server-sdk/src/data_components/memory_store/memory_store.hpp
@@ -3,6 +3,8 @@
 #include "../../data_interfaces/destination/idestination.hpp"
 #include "../../data_interfaces/store/istore.hpp"
 
+#include <launchdarkly/data_model/fdv2_change.hpp>
+
 #include <memory>
 #include <mutex>
 #include <string>
@@ -44,6 +46,8 @@ class MemoryStore final : public data_interfaces::IStore,
 
     bool RemoveSegment(std::string const& key);
 
+    void Apply(data_model::FDv2ChangeSet changeSet);
+
     MemoryStore() = default;
     ~MemoryStore() override = default;
 
diff --git a/libs/server-sdk/tests/memory_store_apply_test.cpp b/libs/server-sdk/tests/memory_store_apply_test.cpp
new file mode 100644
index 000000000..003285c53
--- /dev/null
+++ b/libs/server-sdk/tests/memory_store_apply_test.cpp
@@ -0,0 +1,223 @@
+#include <gtest/gtest.h>
+
+#include <data_components/memory_store/memory_store.hpp>
+#include <launchdarkly/data_model/fdv2_change.hpp>
+
+using namespace launchdarkly::data_model;
+using namespace launchdarkly::server_side::data_components;
+
+// ---------------------------------------------------------------------------
+// kNone tests
+// ---------------------------------------------------------------------------
+
+TEST(MemoryStoreApplyTest, ApplyNone_IsNoOp) {
+    MemoryStore store;
+    Flag flag_a;
+    flag_a.version = 1;
+    flag_a.key = "flagA";
+
+    Segment seg_a;
+    seg_a.version = 1;
+    seg_a.key = "segA";
+
+    store.Init(SDKDataSet{
+        std::unordered_map<std::string, FlagDescriptor>{
+            {"flagA", FlagDescriptor(flag_a)}},
+        std::unordered_map<std::string, SegmentDescriptor>{
+            {"segA", SegmentDescriptor(seg_a)}},
+    });
+
+    store.Apply(FDv2ChangeSet{FDv2ChangeSet::Type::kNone, {}, Selector{}});
+
+    auto fetched_flag = store.GetFlag("flagA");
+    ASSERT_TRUE(fetched_flag);
+    EXPECT_EQ(1u, fetched_flag->version);
+    auto fetched_seg = store.GetSegment("segA");
+    ASSERT_TRUE(fetched_seg);
+    EXPECT_EQ(1u, fetched_seg->version);
+}
+
+TEST(MemoryStoreApplyTest, ApplyNone_DoesNotInitialize) {
+    MemoryStore store;
+    store.Apply(FDv2ChangeSet{FDv2ChangeSet::Type::kNone, {}, Selector{}});
+    EXPECT_FALSE(store.Initialized());
+}
+
+// ---------------------------------------------------------------------------
+// kFull tests
+// ---------------------------------------------------------------------------
+
+TEST(MemoryStoreApplyTest, ApplyFull_SetsInitialized) {
+    MemoryStore store;
+    ASSERT_FALSE(store.Initialized());
+    store.Apply(FDv2ChangeSet{FDv2ChangeSet::Type::kFull, {}, Selector{}});
+    EXPECT_TRUE(store.Initialized());
+}
+
+TEST(MemoryStoreApplyTest, ApplyFull_StoresItems) {
+    MemoryStore store;
+    Flag flag_a;
+    flag_a.version = 1;
+    flag_a.key = "flagA";
+
+    Segment seg_a;
+    seg_a.version = 1;
+    seg_a.key = "segA";
+
+    store.Apply(FDv2ChangeSet{
+        FDv2ChangeSet::Type::kFull,
+        std::vector<FDv2Change>{{"flagA", FlagDescriptor(flag_a)},
+                                {"segA", SegmentDescriptor(seg_a)}},
+        Selector{},
+    });
+
+    auto fetched_flag = store.GetFlag("flagA");
+    ASSERT_TRUE(fetched_flag);
+    EXPECT_TRUE(fetched_flag->item.has_value());
+    EXPECT_EQ("flagA", fetched_flag->item->key);
+    EXPECT_EQ(1u, fetched_flag->version);
+
+    auto fetched_seg = store.GetSegment("segA");
+    ASSERT_TRUE(fetched_seg);
+    EXPECT_TRUE(fetched_seg->item.has_value());
+    EXPECT_EQ("segA", fetched_seg->item->key);
+    EXPECT_EQ(1u, fetched_seg->version);
+}
+
+TEST(MemoryStoreApplyTest, ApplyFull_ClearsExistingItems) {
+    MemoryStore store;
+    Flag flag_a;
+    flag_a.version = 1;
+    flag_a.key = "flagA";
+
+    Flag flag_b;
+    flag_b.version = 1;
+    flag_b.key = "flagB";
+
+    Segment seg_a;
+    seg_a.version = 1;
+    seg_a.key = "segA";
+
+    store.Init(SDKDataSet{
+        std::unordered_map<std::string, FlagDescriptor>{
+            {"flagA", FlagDescriptor(flag_a)},
+            {"flagB", FlagDescriptor(flag_b)}},
+        std::unordered_map<std::string, SegmentDescriptor>{
+            {"segA", SegmentDescriptor(seg_a)}},
+    });
+
+    Flag flag_c;
+    flag_c.version = 1;
+    flag_c.key = "flagC";
+
+    Segment seg_b;
+    seg_b.version = 1;
+    seg_b.key = "segB";
+
+    store.Apply(FDv2ChangeSet{
+        FDv2ChangeSet::Type::kFull,
+        std::vector<FDv2Change>{{"flagC", FlagDescriptor(flag_c)},
+                                {"segB", SegmentDescriptor(seg_b)}},
+        Selector{},
+    });
+
+    EXPECT_FALSE(store.GetFlag("flagA"));
+    EXPECT_FALSE(store.GetFlag("flagB"));
+    ASSERT_TRUE(store.GetFlag("flagC"));
+    EXPECT_FALSE(store.GetSegment("segA"));
+    ASSERT_TRUE(store.GetSegment("segB"));
+}
+
+// ---------------------------------------------------------------------------
+// kPartial tests
+// ---------------------------------------------------------------------------
+
+TEST(MemoryStoreApplyTest, ApplyPartial_AppliesItems) {
+    MemoryStore store;
+    Flag flag_a;
+    flag_a.version = 5;
+    flag_a.key = "flagA";
+
+    Segment seg_a;
+    seg_a.version = 5;
+    seg_a.key = "segA";
+
+    store.Init(SDKDataSet{
+        std::unordered_map<std::string, FlagDescriptor>{
+            {"flagA", FlagDescriptor(flag_a)}},
+        std::unordered_map<std::string, SegmentDescriptor>{
+            {"segA", SegmentDescriptor(seg_a)}},
+    });
+
+    Flag flag_a_new;
+    flag_a_new.version = 6;
+    flag_a_new.key = "flagA";
+
+    Segment seg_a_new;
+    seg_a_new.version = 6;
+    seg_a_new.key = "segA";
+
+    store.Apply(FDv2ChangeSet{
+        FDv2ChangeSet::Type::kPartial,
+        std::vector<FDv2Change>{{"flagA", FlagDescriptor(flag_a_new)},
+                                {"segA", SegmentDescriptor(seg_a_new)}},
+        Selector{},
+    });
+
+    ASSERT_TRUE(store.GetFlag("flagA"));
+    EXPECT_EQ(6u, store.GetFlag("flagA")->version);
+    ASSERT_TRUE(store.GetSegment("segA"));
+    EXPECT_EQ(6u, store.GetSegment("segA")->version);
+}
+
+TEST(MemoryStoreApplyTest, ApplyPartial_PreservesUnchangedItems) {
+    MemoryStore store;
+    Flag flag_a;
+    flag_a.version = 1;
+    flag_a.key = "flagA";
+
+    Flag flag_b;
+    flag_b.version = 1;
+    flag_b.key = "flagB";
+
+    Segment seg_a;
+    seg_a.version = 1;
+    seg_a.key = "segA";
+
+    Segment seg_b;
+    seg_b.version = 1;
+    seg_b.key = "segB";
+
+    store.Init(SDKDataSet{
+        std::unordered_map<std::string, FlagDescriptor>{
+            {"flagA", FlagDescriptor(flag_a)},
+            {"flagB", FlagDescriptor(flag_b)}},
+        std::unordered_map<std::string, SegmentDescriptor>{
+            {"segA", SegmentDescriptor(seg_a)},
+            {"segB", SegmentDescriptor(seg_b)}},
+    });
+
+    Flag flag_b_new;
+    flag_b_new.version = 2;
+    flag_b_new.key = "flagB";
+
+    Segment seg_b_new;
+    seg_b_new.version = 2;
+    seg_b_new.key = "segB";
+
+    store.Apply(FDv2ChangeSet{
+        FDv2ChangeSet::Type::kPartial,
+        std::vector<FDv2Change>{{"flagB", FlagDescriptor(flag_b_new)},
+                                {"segB", SegmentDescriptor(seg_b_new)}},
+        Selector{},
+    });
+
+    ASSERT_TRUE(store.GetFlag("flagA"));
+    EXPECT_EQ(1u, store.GetFlag("flagA")->version);
+    ASSERT_TRUE(store.GetFlag("flagB"));
+    EXPECT_EQ(2u, store.GetFlag("flagB")->version);
+    ASSERT_TRUE(store.GetSegment("segA"));
+    EXPECT_EQ(1u, store.GetSegment("segA")->version);
+    ASSERT_TRUE(store.GetSegment("segB"));
+    EXPECT_EQ(2u, store.GetSegment("segB")->version);
+}