Product Key is found coded in the BIOS.  Use RWEverything (ACPI, MSDM) to get the key from the BIOS, then use it on the activation screen.
As Windows 8 activation key has suddenly decided to deactivate itself after well over a year of use (and no software upgrades and changes) I was wondering where I could find the activation key for my Aurora-R4 so I can reference it while trying to figure out the problem with microsoft (it says the key is already in use elsewhere and since I know that isn't true I'm sure its going to be a fun conversation with them).  Thank you.
Where to find Windows 8 Activation Key