Windows 10 Enterprise E3 VDA (annually subscription for 1 user)

Windows Virtual Desktop Access (VDA) - is an authorization strategy that requires each device seeking access to a Windows virtual desktop in a virtual desktop infrastructure (VDI) to be licensed.  

The goal of Windows Virtual Desktop Access is to simplify licensing requirements in a virtual environment by licensing the devices that seek access to virtual desktops, instead of licensing the virtual desktops themselves. 

Because VDA is included as a feature of Software Assurance (SA), primary users of devices covered by SA can access their virtual desktops at no extra charge. Microsoft defines a primary user as someone who has used the computing device for more than 50% of the time in a 90 day period. 

If the user wishes to access a Microsoft VDI from a device that is not covered by Software Assurance, however, a separate Windows VDA license is required. Such devices include thin clients, zero clients and third-party devices such as contractor-owned PCs.