How to properly license hypervisors with Windows Server and Windows 7?

Question

Microsoft

There is a hypervisor, it has 4 virtual machines running different operating systems:
Windows Server Enterprise 2008 R2
Windows Server Standard 2008 R2
Windows 7
Windows Server Standard 2012 R2
In order not to buy a data center license, can I license two Windows Server Standard 2019 licenses?
Is it possible to license one server with different licenses, for example, there are Standard 2019 and Standard 2008 R2 licenses available, can they be combined to save one 2019 license? How to license a virtual machine with Windows 7 in general, will it need a separate license? How would you license this hypervisor at minimum cost?
Available licenses are Standard 2019, Standard 2008 R2, Enterprise 2008 R2.
PS There are no problems with nuclear licensing, it remains only to distribute which license to use.

Answer 1

If there are 2008R2 licenses, then one windows server 2019 license is enough (in downgrade mode to 2012r2). If Windows Server 2019 is installed as a hypervisor, however, apart from the hypervisor, no services will be raised, then there will even be one license for another virtual machine 2012R2/2016/2019.
But for a client virtual machine, as far as I know, you need a client license.
By itself, the Microsoft hypervisor does not waste licenses - it does not matter to him how many virtual machines are running on it. The main thing is that virtual machines have their own licenses.