How can I tell if my Windows NT installation is a 120-day evaluation or a full version?

A. If you use setup disks that you created with an evaluation CD-ROM, your installation will expire, even if you entered a full-version registered product ID code. However, Microsoft doesn’t provide a method to determine whether your installation will expire or not, which is very annoying because the OS gives you only a 1-hour notice before shutting down.

Download WinInfo from, and the Installation Type value will show either

  • Full version
  • Time Limited Version (nnn days)

Click here to view image

I want to give special thanks to Mark Russinovich at for helping me to decipher the expiry information. However, don’t contact Mark or me to ask for the detection method because we won’t disclose it.

System Internals,, released an excellent command line tool, istrial.exe, which also tells you if your version will expire.

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