The term you're looking for is trial version or copy protection. I have tested ExeShield and it does work with Director executables to create trial software. All copy protection solutions are 3rd party solutions, unless you create your own. You can give the trial version of ExeShield a shot and see if it works for you - that would be my suggestion... or, now that you have some search terms, google and see what other solutions are out there... the key is that not all solutions will work with a Director executable, so always test first.
Many thanks for the info. I've just had a quick look at their website and seems like it is exactly what i'm looking for.