If you make certain hardware changes, Windows 10 will not recognize it as the same PC that received the free upgrade. Changing the motherboard, for example, will give you a brand new BIOS chip, which contains the software licensing description table, or SLIC, a digital signature placed inside the BIOS by the OEM. When this digital signature changes, Windows 10 will de-activate. Windows 10 will no longer be able to activate from the activation server automatically. Fortunately, Gabe Aul of Microsoft, has tweeted that you can just contact Microsoft Support in order to regain entitlement. You can contact Microsoft Support from within Windows 10, explain the situation, and they\’ll get Windows 10 activated for you. Just launch the Contact Support app included in Windows 10. (This can be run from the Start Menu -> All Apps.) Navigate to the Services & apps -> Windows -> Setting up category, which includes activation issues. From there, you can text-chat with a Microsoft support representative or have a Microsoft support person call you by phone.
Maybe because its free for now ? have tried this in Windows 7 era and that did not work, MS didn�t care about my burned MB.At least not in brazil. But I have a question about doing a fresh install, I�ve upgrade all my 3 PCs at home with W10, all of then with a purchased Win 8 Professional, and when I check my Keys all 3 PCs have the same key, and for my surprise my work computer which was running a Windows 7 Jack Sparrow Edition got the same Win 10 key after upgraded. What key should I use to do a fresh install ?