

Microsoft switched from the licensing model of physical processors to the core licensing model (Core-based) in Windows Server 2016 and Windows Server 2019. For example, for a 4-processor server you will need 2 Windows Server 2012 R2 licenses. If a physical server has more than two processors, you will have to buy one license for each pair of processors. You cannot split one license for two single-processor servers (in this case you will have to purchase two Windows Server licenses). one license covers up to two processors (sockets) located in one physical server (cores are not processors!). One license of Windows Server 2012 R2 allows you to run the OS on one single- or dual-processor server. Per-Socket Licensing in Windows Server 2012 R2

It should be noted that Web Server edition has been eliminated completely. These OSs have a number of specific limitations and no rights for virtualization. We don’t consider Essentials and Foundation Windows Server editions, since they are designed for small businesses. In fact, when choosing Windows Server 2012 R2 Edition you need to decide whether you will use virtualization or not.

In most cases, when considering the Windows Server licensing model, it is advisable to consider the Standard and Datacenter Windows Server editions.
