Follow the on-screen instruction to end the process, followed by a quick Restart.While all the keys are verified, one or the other key may not work due to over-usage. If one key fails to activate, try another key. Enter the 25-character Windows 8.1 serial key in the text box.This will prompt the Windows activation app to open.In the dialog box under the search bar, enter “slui 2”.Make sure to Turn Off Windows Update feature to avoid error while activation.Disable any antivirus program before activation.To get the best performance out of the installed copy of Windows OS, patiently follow the given steps to activate using any one of the given product keys. Procedure to activate Windows 8.1 with a Windows 8.1 serial key Having gone through the above exciting new features, one would want to upgrade to Windows 8.1 OS for which an activation with a Windows 8.1 product key is necessary. Major technology upgrade via integration support for 3D printing and Resilient File System.The extensive and wide search algorithm for system tasks.Better Integration with Microsoft SkyDrive.Stable and better version of Microsoft Edge.Upgrade to Music and Video app interface.