I have a copy of Windows 8.1 Enterprise Evaluation. When will it expire and can I upgrade to keep it?
Windows 8.1 Enterprise Evaluation is specifically designed for IT professionals interested in trying out Windows 8.1 Enterprise on behalf of their organization. Your license will expire 90 days after activation. You must activate the evaluation copy before October 21, 2014.
You cannot upgrade from the evaluation copy to a licensed working version of Windows 8.1 Enterprise. A clean installation is required.