title: How to Make/Set a time limit by date for my java program
body: <p>I am working with java application programs,especially billing software.</p>
  
  <p>I want to gave my application program as demo version for customers.
  So I want to set my program for a limited period of time(30 days Trial),
  and after that It should ask for a valid key for continuing.</p>
  
  <p>How is it possible to Set a 30 days time period for my application in Java.</p>
  
  <p>Any Idea is acceptable</p>
  
  <p>Thanks in advance..</p>