How to set the Expire Period of dot net dll/assembly

Question

Hi Teams...

How to set the Expire Period of dot net dll/assembly .It work 15 days form the date of Setup and Instal the Application after that it will not work.Like trial period of a product.I Don't Have any Ideals if any body have any Lin url/ ideal/Advice plese tell me.

How/Where to set the expire date .How to take the Sys Date,Sys Unique Identyfire.where to write the code.Whate name space/Class requre.please describe the login.

Thank's

Prasanta Kumar Pradhan

http://globaltouch.in