Where is my Windows 10 product key?

The license keys are customer centric information. Dell does not have access to them.

The product keys are embedded on the motherboard and sometimes associated with your Microsoft account (if logged in with your Microsoft account). This means if you need to reinstall Windows 10, it will get automatically licensed.

In cases where you need to type your Product Key, you can either find it by using:

Cmd command

1. Press Windows + R key to open the run dialog box, then type in cmd and hit Enter. 

2.  Paste or type in the following command wmic path softwarelicensingservice get OA3xOriginalProductKey and hit Enter.

You should see the key on screen below the line that says "OA3XOriginalProductKey.

Useful link: How to Find Your Windows 10 Product Key Using the Command Prompt

or

Third Party Apps (Nirsoft Product Key Finder)

Policy note = Third party apps are to be used at your own risk.