title: Does Windows provide a unique identifier I could use to enforce a free trial?
body: <p>Does the Windows operating system contains any unique computer/OS id? </p>
  
  <p>This is for my own software. I want to create 30 day trial/demo version.</p>
  
  <p>Here is what I want to do:</p>
  
  <ol>
  <li>When someone installs a trial I grab the unique ID, send it to server.</li>
  <li>After the 30 day trial, if software is reinstalled, the server blocks the trial version.</li>
  </ol>
  
  <p>So the real question is: Does Windows contains any unique IDs I could rely on?</p>
  
  <p>I think that IP address is not a reliable option.</p>