If you are testing an evaluation version of Windows 8.1, you might be inconvenienced because Microsoft does not support any way to convert the evaluation edition to the full enterprise edition with a public KMS key like it is possible for Windows Server 2012. You cannot change the edition with DISM commands in Windows 8.1. Even if you download the ISO image of the enterprise edition of Windows 8.1 and try to upgrade the OS, it will not allow you to proceed.
Here is a workaround which lets you upgrade Windows 8.1 Evaluation to the Full version easily.
