For some reason the 64bit download of Windows 8 Enterprise from TechNet does not prompt for a license key but does try and activate – and then fails every time. When it does enter the normal activation process you’re likely to see a DNS error or something along the lines of being unable to connect to the remote activation service.
So credit to the forum at Techplex for the simple solution, albeit unclear why it is needed in the first place.
Solution: Right-click in the lower left screen corner and open a command prompt as admin. Type in the following and hit Enter.
The Windows Activation process will start, you can enter your TechNet license key and then the app will connect to the remote system and you should then have a properly activated Windows 8 device.