I'm getting an new PC in a few weeks and I'm going to attempt to downgrade it from win 10 to win vista or win 7. If that doesn't work I will at least do a clean install of win 10 on the pc to remove all the pre-installed crap. I need to know how can I backup my license for re-activation of win 10 in case I'm stuck using it. I know you have a product key in the past, but now I hear that windows 10 does not use that so I'm confused as to how to re-activate windows 10 if I have to.
W10 (pro and home) will reactivate itself the first time you connect to internet, on a PC where it was previously activated. Anyway you can backup it making a copy of C:\ProgramData\Microsoft\Windows\ClipSVC\token.dat (be sure the clipservice is stopped before copying/restoring it)
Is it a brandsystem (win 10 Home pre-installed)? If yes, it has an oemm bioskey for 10 Home and you'll always be able to reinstall the correct win 10 version, in your case Home, by using the Multiple Editions ISO and it will auto-activate using the oemm bioskey. To find out you can use the OEM_Query_Tool from the Multi_OEM/Retail project by The_Guardian.