I have a software product written in VB6. It is a paid software product and it has a demo version for 1 month.There is no separate setup file for demo version.The software on entering the product key turns demo to a full version.I used to write the information in registry to track the 1 month for demo version and after that software will not work. Also if windows user is not admin then registry cannot be written to HKLM. If i write registry to HKCU the user can create new user and reuse the software by installing it. So how can i manage the demo version to 1 month and user cannot use it after 1 month without purchasing the key?
I would have thought that you would need to create a license key file and store it with the .exe file. It should be encrypted in some manner and would hold details of when it was created and on what machine etc. You could probably circumvent it but it would certainly be robust enough for your requirements.