title: Is there a file updated always in the windows system, which update includes the time information?
body: <p>I am programming a 30-Day-trial application, I need to make sure if the user changes the system time it will not harm my application and the 30-day-trial will still be calculated, or at least I will be able to figure he did something wrong.</p>
  
  <p>The best way I found is to check for a system file which its contents updated and every update contains the time with its data, so I can find out if the user changes the date or not, by comparing the dates with each other ...</p>
  
  <p>I know it is not certain way, but it is kind of make it harder and shrink the area of who can crack it.</p>