One method is to enter 'wmic path SoftwareLicensingService get OA3xOriginalProductKey' in Command Prompt This article explains a few different ways for how to find a Windows 10 product key.

You can also find Windows product key using VB Script. If you are looking for an easier way, you can also use some free Software Key Finders to recover and save, not just Windows, but even Office ...

There is this simple software key finder called Windows OEM Product Key Tool that can help ... not just Windows, but even Office, Software, Games serials and license keys.