Create a Windows application with serial validation at run time

Hi Friends. ,
          I need one help. . How to create a windows application with serial key validation. . I create a setup and deployment project and sets the serial key format. . But it doesn't validate at run time. . Applications any key. .

      I need an Application which accepts the serial key which i specified in the program and allow the user to proceed. . For that, where i have to validate the serial key. . Tell me procedure or class to validate. .

Reply me. .


Regards
Prasath