We are virtualizing Microsoft Windows 7 and Windows 10 upgrade licenses on VMware platforms. The Microsoft licenses are volume licenses purchased under an Enterprise Agreement. How do we have to license the access to those virtual OS clients?

You may access up to four virtual Operation System Environments (OSEs) as long as the operating system licenses are covered by active Software Assurance. If licensing per User applies, each licensed user may remotely access up to four OSEs. If licensing per Device applies, up to four OSEs may be remotely accessed from each licensed device.

If you need to access more than those four virtual OSEs, additional licenses are required. In this case, the licensed user or the licensed device needs to be fully lincensed again. Thus, the user/the device acquires four additional licenses to access a virtual OSEs.

The same licensing logic applies when remotely accessing physical OSEs.

Source: Microsoft Product Terms, Mai 2018