How to free a Pascal function's TStringList?

I've got a function in Pascal which returns a StringList as the result. How do I free it correctly? As it's not a global variable I can't free it in the Form.FormDestroy procedure. And freeing it after returning it doesn't work either (that should be allowed though, LOL).

In general, is there a way to free all objects (including the ones that the form has no control over) as soon as the program is closed?

Solution

@TomBrunberg is right, his comment solved the problem:

Take a reference to the returned TStringList and use that ref to free it:

var 
  sl: TStringList; 
begin
  sl := fnThatReturnsAStringList; 
  UseTheList(sl);
  sl.Free; 
end;

Another possibility, in case you call the function only because of side effects of that call, without any interest in the returned TStringList, you may even free it simply by calling:

begin
  fnThatReturnsAStringList.Free;
end;