Recently Microsoft announced the availability of Windows 8.1 and Windows Server 2012 R2 for TechNet and MSDN subscribers, but failed to suggest when Windows 8.1 Enterprise version would be available for download.
Today, Microsoft has stated that Windows 8.1 Enterprise RTM bits is now available for download.
Beginning today, TechNet and MSDN subscribers will now have access to Windows 8.1 Enterprise RTM. This also includes access for Volume License (VL) customers with an active Software Assurance (SA) agreement, as you receive a TechNet subscription as part of SA.
Read the full statement: Windows 8.1 Enterprise RTM Now Available To Volume License Customers