New
#11
If you have performed an upgrade of windows 10 over an activated windows 7, then the device has got the digital entitlement; so it will remember the key when you will attempt a clean reinstall. But if you want to avoid this, please pay attention to what @NavyLCDR posted.
Without it we cannot see the exact situation, so specific help will not be possible.
I would suggest you to not use linux (GRUB) in the same HDD with windows.