I know this sounds like a common topic, but hear me out :)
I'd like to make my application a trial version. I don't have any problems with *how* to do it (disabling certain application features after set number of days, etc), but rather how to do it as foolproof as possible. Most posts I've searched for recommend using registry keys to set the install date and check against that on program start-up. But that's exactly where most people would look for such a key, and delete it. Checking for the existence of the key on program start-up is one way to protect against the key being deleted, but then they can just reinstall the software and be able to use it again for the next 30 days, etc. Thus, a neverending circle.
So, any other ideas? Or some obscure, hard-to-find (yet acceptable) location to save such a registry key? Or, well, anything?