Windows 8.1 Product Key: Windows 8.1 is the successor to windows 8 operating system by Microsoft. It has all new features of Windows 8 and updating to windows 8.1 is free for the users who are using windows 8. It had updated features than windows 8, which made it attractive to the users. To run windows 8.1 we need windows 8.1 activation key. Let’s get some information about windows 8.1 key.