How to license Windows Server in non-standard situations?

Question

Licenses for software and other works

Windows Server 2003 - Windows Server 2012 R2 is licensed by processor. Windows Server 2016 - Windows Server 2019 are licensed by core. There are also special editions that are statically licensed. But they are either very difficult to buy, or they only go through the OEM channel. One license is suitable for 2 cores (2 processors, respectively) and you need to buy as many licenses as there are physically cores (or processors) on the servers. Question: Windows Server has a regular activation module, which is activated by a key. Where to register all licenses?
However, do not forget about the point: "The Standard license gives the right to use 2 virtual machines, the datacenter license gives the right to use an unlimited number of virtual machines." If Windows Server is used as a host system and Windows Server is also used as a guest, then we simply buy licenses according to the number of cores. And if:
1) Windows Server is used as a host, and Windows, Linux and BSD are used as a guest.
2) Windows, Linux, BSD is used as a host, and Windows Server as a guest.
How to acquire licenses in this case?

Answer 1

How to acquire licenses in this case?

in the same way - eight 2-core licenses or one 16-core minimum... all physical cores are
licensed ...

Extract from the first document

Windows Server operating system software under the Per Core/CAL license model is licensed by physical core. Customers have the choice of licensing a server for either Windows Server Standard or Windows Server Datacenter. In either case, all of the physical cores on the server must be licensed (subject to a minimum of 16 per server and eight per processor). Windows Server license terms permit customers to run up to two instances of Standard per Licensed Server (e.g., on the physical server and in one guest VM (referred to as “virtual operating system environments” or “virtual OSEs” in licensing), or in two guest VMs) and unlimited instances of Windows Server Datacenter per Licensed Server. Customers needing more than two VMs on a server licensed for Standard edition have the option of relicensing all of the physical cores on the server to permit two additional running instances. Additionally, if the Physical OSE is used only to support VM workloads, the same licenses permit use of Windows Server as the host operating system.

Extract from the second document

Windows Server licensing permits use of the software in both the physical OSE (an instance of the software serving as the host operating system (or OS) in the case of a virtualized server) and virtual OSEs (instances of the software running as guest OS’s). If Windows Server is deployed on a server running a hypervisor on bare metal (directly on top of the server hardware), such as VMware’s ESX/ESXi, then Windows Server will not be deployed as a host OS in the physical OSE. However, the guest OS instances deployed and running in virtual OSEs on the server still must be appropriately licensed. This means licenses must be assigned to the server for all the physical cores on the server (subject to a minimum of eight per processor and 16 per server). Standard edition will allow up to two instances on each fully licensed server (plus a third instance in the physical OSE, if it is used solely to host and manage virtual OSEs) and Datacenter edition will allow an unlimited number of instances on each fully licensed server. (The right to run an instance of Windows Server in the physical OSE is not relevant in the case of ESX/ESXi hosting the virtualization layer.)