*Note: Keep in mind that the following utilities cannot retrieve the Windows Product Key on OEM pre-installed computers. How to retrieve the Windows 8.x /Windows 10 / Office Product key(s) from registry. – If you have typed before the Windows 8.x or Windows 10 product key to install Windows, then you can use on of these these programs to retrieve the key from the registry. – If you purchased Windows 8.x, 10 or Office online, then you can find your unique Windows or Office product key in the online order info or in the confirmation email or in the DVD package. Windows 8.x or Windows 10 (Purchased Online). Windows 8.x or Windows 10 (OEM – BIOS Product Key).Windows 8.x, Windows 10 or Office (Purchased Online).How to View the Product Key in Windows 10, 8.x, 7, Vista or XP. In this tutorial you can find instructions on how to find or to retrieve (from Registry or BIOS) the Windows or Office Product key(s) in order to re-install Windows (or Office) on your computer. In Windows 7, Vista or XP computers the Windows product key is commonly found on computer's case but in Windows Windows 10 and Windows 8 systems the Windows product key is embedded in BIOS. If you 're preparing to reinstall Windows, then you need the Windows product key for installation and activation.