You can use the following method to get your Windows 10 Product Key. This can be useful specially if you are dealing with a pre-installed Windows or you have upgraded to Windows 10 from Windows 7, 8 or 8.1 and for any reason you need to know the product key.
First you need to open up command prompt:
Press WINDOWS LOGO key + X key > Click Command Prompt (Admin)
Copy and paste the following code:
wmic path SoftwareLicensingService get OA3xOriginalProductKeyThen press Enter to find your product key.