This method to recover Windows product key is very simple. All you need to do is fire up a Windows Command Prompt window with administrative purposes. To do this, search for cmd in Windows search bar and right-click to choose the elevated permissions option.
Now, type the following command in Command Prompt and hit Enter:
wmic path softwarelicensingservice get OA3xOriginalProductKey
This step will promptly show your Windows key. Note that this method also works for OEC and Retail licenses.