The installation of the Windows 8 operating system is pretty straightforward and users do not need to enter a product key during installation. It may however come as a shock to some users while re-installation when they they have to enter the Windows 8 product key .
Also see: How to Install Windows 8 From USB Drive
The problem here is that Microsoft is not supplying the product key with the operating system. You won’t find it in a text document that is part of the installation files nor on the official website.
Windows 8 Operating System Product Key
A Microsoft employee replied has provided the solution for this issue @ Microsoft Developer Network forum:
If you need to reinstall Windows Developer Preview or use the Reset functionality, you might be asked to enter this product key:
If you’re running a server version of Windows Developer Preview, you can use this product key:
Note: These product keys are only for use with the Windows Developer Preview version of Windows 8.
There you have it. The keys are only compatible with the developer preview of Windows 8. However tt will wont work in the beta or the final version of the operating system.