I wish to implement my software on a shareware basis, so that the user is given a maximum trial period of (say) 30 days with which to try out the software. On purchase I intend the user to be given a randomly-generated key, which when entered enables the software again.
I've never been down this route before, so any advice or feedback or pointers to 'standard' ways of how this is done would be much appreciated.
I do not anticipate users cheating by changing the system date or anything like that, though this is probably worth considering. Apologies if this topic has appeared before.
With regards to a random-generated key, how will you verify a key is legit or if a key is bogus if it is actually random? Have a look at the article "Implementing a Partial Serial Number Verification System" as it is quite good and is easy to implement in any language.
With regards to time trials, as basic solution would be to compare your main executable files creation time to the current system time and act on the difference. This assumes your installer sets the files creation time to the time of install as opposed to preserving the time you compiled it! :)