diff --git a/hamilton/caching/stores/memory.py b/hamilton/caching/stores/memory.py
index a0f8af8fc..37eee89d5 100644
--- a/hamilton/caching/stores/memory.py
+++ b/hamilton/caching/stores/memory.py
@@ -276,6 +276,4 @@ def load_from(
             result = result_store.get(data_version)
             in_memory_result_store.set(data_version, result)
 
-        # TODO could be beneficial to delete the `result_store` after loading from it,
-        # but we don't know if it's used for other purposes
         return in_memory_result_store
diff --git a/tests/caching/metadata_store/test_memory.py b/tests/caching/metadata_store/test_memory.py
index 9cba2ea86..d0f76d1b4 100644
--- a/tests/caching/metadata_store/test_memory.py
+++ b/tests/caching/metadata_store/test_memory.py
@@ -7,12 +7,11 @@
 # a pytest fixture automatically provided to tests
 from .test_base import _mock_cache_key, metadata_store  # noqa: F401
 
+# implementations that in-memory metadata store can `.persist_to()` and `.load_from()`
+PERSISTENT_IMPLEMENTATIONS = [SQLiteMetadataStore]
 
-@pytest.mark.parametrize(
-    "metadata_store",
-    [SQLiteMetadataStore],
-    indirect=True,
-)
+
+@pytest.mark.parametrize("metadata_store", PERSISTENT_IMPLEMENTATIONS, indirect=True)
 def test_persist_to(metadata_store):  # noqa: F811
     cache_key = _mock_cache_key()
     data_version = "foo-a"
@@ -38,11 +37,7 @@ def test_persist_to(metadata_store):  # noqa: F811
     assert in_memory_metadata_store.get_run_ids() == metadata_store.get_run_ids()
 
 
-@pytest.mark.parametrize(
-    "metadata_store",
-    [SQLiteMetadataStore],
-    indirect=True,
-)
+@pytest.mark.parametrize("metadata_store", PERSISTENT_IMPLEMENTATIONS, indirect=True)
 def test_load_from(metadata_store):  # noqa: F811
     cache_key = _mock_cache_key()
     data_version = "foo-a"
diff --git a/tests/caching/result_store/test_memory.py b/tests/caching/result_store/test_memory.py
index 8935f9ee3..7d7fc87e3 100644
--- a/tests/caching/result_store/test_memory.py
+++ b/tests/caching/result_store/test_memory.py
@@ -8,6 +8,9 @@
 # a pytest fixture automatically provided to tests
 from .test_base import result_store  # noqa: F401
 
+# implementations that in-memory result store can `.persist_to()` and `.load_from()`
+PERSISTENT_IMPLEMENTATIONS = [FileResultStore]
+
 
 def _store_size(memory_store: InMemoryResultStore) -> int:
     return len(memory_store._results)
@@ -88,11 +91,7 @@ def test_delete_all(memory_store):
     assert _store_size(memory_store) == 0
 
 
-@pytest.mark.parametrize(
-    "result_store",
-    [FileResultStore],
-    indirect=True,
-)
+@pytest.mark.parametrize("result_store", PERSISTENT_IMPLEMENTATIONS, indirect=True)
 def test_persist_to(result_store, memory_store):  # noqa: F811
     data_version = "foo"
     result = "bar"
@@ -109,11 +108,7 @@ def test_persist_to(result_store, memory_store):  # noqa: F811
     assert memory_store.get(data_version) == result_store.get(data_version)
 
 
-@pytest.mark.parametrize(
-    "result_store",
-    [FileResultStore],
-    indirect=True,
-)
+@pytest.mark.parametrize("result_store", PERSISTENT_IMPLEMENTATIONS, indirect=True)
 def test_load_from(result_store):  # noqa: F811
     data_version = "foo"
     result = "bar"