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You can use a licensing system like CryptoLicensing which supports trial/full schemes, date based expiry, etc.
or Quote:
1. create an installer for ur application, record the date it was installed and check the date everytime the application starts , when it does expire just shutdown the application.
2. if you use a datadriven application using a database dont allow users to login after the date expires with setting the date from the first time logged in.
3. editing the registry of client machines the application has been installed and check the registry everytime the application starts and do accordingly
Regards,
Praveen Nelge