I want to reinstall Windows from scratch, but I was lost in the license terms when I upgraded to W10. How can I be sure my license will transfer to the next install? Do I need to get my license key? Is it dependant of the current hardware it's installed in? Where can I see the license properties? I have a Windows 8.1 Pro 64 bits that was upgraded to W10 Pro in 2014. Also my Windows 10 key isn't the same as the original W8.1 key, but I suppose this is normal.