₦airaland Forum

A common way to create a trial is to limit usage days (say 30 days). You can do this by storing the current date in an obscure registry key, when the software is first run (or during installation). Then you check whether the limit has passed everytime your software runs.

For a readymade system which does this, see CryptoLicensing ( http://www.ssware.com/cryptolicensing/cryptolicensing_net.htm ) - it also has other scenarios like max executions, max runtime in minutes, etc.

CryptoLicensing http://www.ssware.com/cryptolicensing/cryptolicensing_net.htm can do eval/trial licenses, annual licenses, etc. Its quite easy to integrate in your app.