Create an application that will expire after a trial period [duplicate]

Answer 1

Your options:

1. At the installation write something to the registry, so that it is hard to find and remove later. This way your application will know when it was originally installed and whether it should still work right now or stop. This method will fail if the registry is cleaned well or if the OS is reinstalled.

2. Use some sort of online validation service. Will be free of the disadvantages of the [1]. Will also allow you to monitor application activity transcending the OS installation. For that to work you will need to somehow uniquely identify a user PC and transmit its signature to your server.