I barely remember way way back in late 80's, in the times of physical disc distributions, you could not allow copies to be made by embedding disc number into the exe when compiled from QB. If the exe found itself on wrong disk number it deleted itself. You could have probably done that with dates as well for time limit samples.
724 855 599 923 575 468 400 206 147 564 878 823 652 556 bxor cross forever

