diff --git a/mathstream/__init__.py b/mathstream/__init__.py
index 8814edf..5395486 100644
--- a/mathstream/__init__.py
+++ b/mathstream/__init__.py
@@ -1,6 +1,12 @@
 from .engine import clear_logs, add, sub, mul, div, mod, pow, is_even, is_odd
 from .exceptions import MathStreamError, DivideByZeroError
-from .number import StreamNumber, free_stream, active_streams
+from .number import (
+    StreamNumber,
+    free_stream,
+    active_streams,
+    set_manual_free_only,
+    manual_free_only_enabled,
+)
 from .utils import collect_garbage, tracked_files
 
 __all__ = [
@@ -18,6 +24,8 @@ __all__ = [
     "StreamNumber",
     "free_stream",
     "active_streams",
+    "set_manual_free_only",
+    "manual_free_only_enabled",
     "MathStreamError",
     "DivideByZeroError",
 ]
diff --git a/mathstream/number.py b/mathstream/number.py
index 1cad0bd..96a299a 100644
--- a/mathstream/number.py
+++ b/mathstream/number.py
@@ -12,6 +12,7 @@ from .utils import (
 )
 
 LOG_DIR = Path("./instance/log")
+_MANUAL_FREE_ONLY = False
 
 
 def _ensure_log_dir() -> None:
@@ -138,6 +139,8 @@ def _decrement_active(path: Path, delete_file: bool = True) -> None:
 
 
 def _finalize_instance(path_str: str) -> None:
+    if _MANUAL_FREE_ONLY:
+        return
     _decrement_active(Path(path_str))
 
 
@@ -149,3 +152,14 @@ def free_stream(number: StreamNumber, *, delete_file: bool = True) -> None:
 def active_streams() -> Dict[str, int]:
     """Return the active StreamNumber paths mapped to in-memory reference counts."""
     return dict(_ACTIVE_COUNTER)
+
+
+def set_manual_free_only(enabled: bool) -> None:
+    """Toggle whether garbage collection happens only via explicit .free() calls."""
+    global _MANUAL_FREE_ONLY
+    _MANUAL_FREE_ONLY = bool(enabled)
+
+
+def manual_free_only_enabled() -> bool:
+    """Return the current manual-free-only toggle."""
+    return _MANUAL_FREE_ONLY