It always ends up as a boolean somewhere. /* complicated auth check */ ... /* more complicated auth check */ ... /* etc */ if(!isValid

It always ends up as a boolean somewhere. /* complicated auth check */ ... /* more complicated auth check */ ... /* etc */ if(!isValid) { /* do nasty things */ ... } You just need to find isValid and flip its value. Easy cheese in a good debugger. I used to keep Soft-ICE installed on all my boxes. There were a few copy protected apps I didn't bother writing out the cracked file since I used them infrequently. Instead I'd set a breakpoint right before the e.g. isValid flag. Whenever I'd run those apps, Soft-ICE would pop up and I'd know I need to flip the bit for the full version.