So if I upgrade to Windows 10 using my Windows 7 serial number, is that key locked to my custom built PC for life? Is this confirmed to be the case? So if change the CPU and mobo to the new Intel Skylake platform in the future, will I have to buy a new Windows 10 license? It makes no sense to me that should be the case because I bought my Windows 7 software from a retail store rather than buying a computer with Windows 7 pre-installed.