There were times that we need to refresh our system once in a while like reformatting the hard drive of the desktop pc. For every installation of any Windows operating system, it asks for the license key that you have used on that machine. What if you have forgotten the license key, that's a real problem. So, before you refresh your machine, you need to retreive the license key of your Windows operating system. There's this software that is very useful and can able to get that license key, it's Belarc Advisor, and you have just to install it into your computer and run the software. Scroll through the section on the license keys, like on the screenshot below.