>The problem with date()is that the user can simply change their system date and can continue to use the application indefinitely. I would like something a little more secure.


I create a file hidden in the depths of the windows directory with an obscure name the first time the application runs, which holds the StartDate, which is the day it is first run, LastAcessDate which is the last time it is run, and the EndDate, which 30 days from StartDate.

If the user tries to set the clock back LastAcessDate will be before DATE() and the system notifies them that date tampering has been detected and shutsdown.

And by hiding this file out of the application directory if they unistall/delete the app and try to reinstall it won't let access the program. The only way to break the lockout is to find the hidden file and delete it.

Of course they could always just install it on another machine anyway.