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 Windows Server 2012 R2 Datacenter – you can run an unlimited number of virtual machines on a single physical host (recall that such virtual machines can be easily activated using the AVMA – Automatic Virtual Machine Activation).

Windows Server 2012 R2 Standard – the license allows to run only up to two virtual machines.It means that you choose the edition depending only on the number of virtual machines on the physical host instead the availability of the required features. The features of the Standard and Datacenter editions of Windows Server 2012 R2 is almost identical except for the license rights to run virtual machines. In most cases, when considering the Windows Server licensing model, it is advisable to consider the Standard and Datacenter Windows Server editions. Calculating Windows Server Licenses for Virtualization.Windows Server Licensing and VMs Migration between Physical Hosts.Understanding Windows Server Virtual Machine Licensing.Per-Socket Licensing in Windows Server 2012 R2.

How can i buy windows server 2012 r2