The Windows 10 product key is a sequence of 25 letters and numbers divided into 5 groups of 5 characters each (ex: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX) that is used to activate the 32-bit or 64-bit Windows 10 edition that you have installed.
OEM PCs store and encrypt the product key in the UEFI firmware chip. The product key is no longer on a COA sticker to help prevent theft. When you reset or install Windows 10, the product key will automatically be detected from the UEFI firmware chip, and will be used to activate.
When you install an Insider Preview or retail copy of Windows 10, you will need to enter it’s product key during installation.
Windows 10 Enterprise does not require you to enter a product key during installation. You will have a free 90-day evaluation period before you must change the product key to be able to enter your volume license product key and activate.
This tutorial will show you how to view the installed and OEM product key in Windows 10.