How to find your Windows 10 product key
If you upgrade your computer from Windows 7 or Windows 8 to Windows 10, you probably have no idea what your product key is for the latest version of the operating system. The time may come when you want to perform a clean installation of Windows 10, and this is when you'll need that key.
It is not possible to use your product key for your old version of Windows to activate Windows 10, but during the initial upgrade process this key is converted into a new one. Using a special tool, you can find out the key that has been generated for you so you can make a note of it for future reference.
There are actually numerous tools that can be used to determine your Windows 10 code. One of the more reliable and comprehensive is ProduKey which is available free of charge -- there are 32- and 64-bit versions of the software available, so make sure that you download the correct version for your system.
ProduKey is provided as a compressed file, so unzip it and then run it. In a matter of seconds you'll be provided with the key you need which you can then make a copy of, email to yourself, write down, or backup in some other way for when you need it.
Grab a copy of ProduKey from the Nirsoft website.