Sysprep does not remove product key

So I was given a disk by our purchasing group, Windows 7 install disk.  After installing it, I realized that the key was baked in some how. No big deal.  Well when it came to sysprep time, it was a big deal.

Here is the problem.  When trying to sysprep in general, not yet using an unattend file, it never asked for a product key.  I needed it to ask for one because I had some individual keys I had to manually enter.

Here is what I figured out.

First run the command -> slmgr.vbs /dlv

This will give you information about the way it's licensed.

Mine said Microsoft Windows 7 VOLUME_KMSCLIENT channel.  That was odd.  It should say Microsoft Windows 7 Professional.

I then thought this might work. If you were to update it with a product key that is on the computer, it might get rid of the KMS configuration and reset it back to a standard client.

So I did -> cscript slmgr.vbs /ipk <insert product key here> (one time it worked with cscript the other it didn't)

I then reran slmgr.vbs /dlv and now it says Microsoft Windows 7 Professional.

Now it was time to try just sysprep, no unattend file.

I ran c:\windows\system32\sysprep\sysprep /generalize /oobe

It rebooted and went through the sysprep process.  And voila! it now prompted me to enter my key!

Source:  Link