Update bpm-activities.md

Author: yurikuzn

docs/administration/bpm-activities.md

@@ -111,6 +111,10 @@ When using Formula in a task that creates or updates another record, the current
 
 If the parameter *Isolate Variables* is checked, Formula variables defined within the task won't be exposed outside of the task. The *Return Variables* parameter allows to specify variables that will be exposed.
 
+!!! note
+
+    If you didn't check the *Isolate Variables* parameter, be aware that all variables defined in Execute Formula Script actions will remain available throughout the process and even after it finishes. Since some variables may contain sensitive data or consume disk space, it might be reasonable to unset them at the end of the script. Checking the Isolate Variables parameter is recommended.   
+
 ----
 
 ## Send Message Task