I purchased a used MS Surface Pro on eBay. It was delivered being factory-reset and the OS is Windows 8.0. When I tried to upgrade it, it asked me to input Product Key which I don't have. I did some research and factory-reset seems to make the product key lost.

How can I upgrade it to Windows 8.1?




It's free in the Windows Store (i.e. no license required), you may need to make a Microsoft account to access it, however.

If you install through the Windows Store and are getting that message, you are likely not running an activated Windows 8 copy. The key is stored in the UEFI, so try activating from My Computer > Properties. If that fails, you may need to call.


If your PC is currently running Windows 8 or Windows RT, it's free to update to Windows 8.1 or Windows RT 8.1. And unlike previous updates to Windows, you'll get this update from the Windows Store.

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