You can always "re-activate" a copy of windows by calling the toll free number that pops up when you try to active it. You simply call Microsoft and talk with a machine. Keying in some numbers from the OS and get 18 or so numbers back, which you need to input in windows. Then it's registered to your current build (mobo). I have done that numerous times when changing mobo. Even with Office. But you can buy a win10 license from ebay for as little as 2 or 3$.