Unfortunately, I am having problems with this activation method.It will say "Windows is activated" and the product key will end in H8Q99 (Home) or 3V66T (Pro).
After that your hardware ID is registered on Microsoft's activation servers and will automatically reactivate without a key on the clean install (hit Skip every time it asks for a key and it will activate when you login for the first time)
This won't work so well if you use a virtual machine + Bootcamp, however.
I have a 2011 Mac Mini which had Windows 7 on a SSD partition with OS X. I have updated it to Windows 10 several times and have received the "Windows Activated" status ... although I was having trouble getting the Mac BootCamp wireless mouse driver installed (it works fine, but lacks the gesture features). I have tried both the download update, and the .iso thumb drive update methods.
I decided to start over with a "clean" install of Windows 10 from the .iso installation USB drive. It installed fine and updates fine ... but refuses to activate with the Microsoft servers, even though it did so previously with the upgraded existing Windows 7 system. The version 5 BootCamp drivers installed fine and the wireless mouse is fully operational. I have tried this several times with the same results (thanks WinClone!)