After I updated to Win10 successfully I ran Belarc Advisor 8.5 and determined that a NEW key code had been generated during the upgrade process - this key code was identified as being for Win10 Professional. So, I would guess here that I could use this same key code if sometime in the future I opted to do a clean install using the ISO file I had previously downloaded or the flash drive I created that held both the 32 bit and 64 bit versions. That conclusion is my own and one that I have not seen verified by anyone from Microsoft or elsewhere on line.