The Windows Server licensing is simpler than in the past. If you're planning to run 10 VMs and up, then the Datacenter licensing is cheaper… but read on. When you grow up and If you have 2 standard licenses assigned to a single physical host, then you can run four Windows Server VMs etc…. It's better explained with an image. The image comes from the original Microsoft PDF document referenced at the bottom of the post. As you can see, there are 3 physcial hosts. The one on the left has two standard licenses, while the two others do have three standard licenses.
First the licensing role needs to be installed. Activate Licensing Server: Now the RD Licensing role is installed we need to activate it with Microsoft. To do this we need to launch the Remote Desktop Licensing Manager.
Minimum Hard Drive Space: Windows Server R2 offers exciting features and enhancements across virtualization, storage, networking, virtual desktop infrastructure, access and information protection, and more. Windows Server R2 offers, windows server 2012 r2 license virtualization and cloud platform that can scale to continuously run your largest workloads while enabling robust recovery options to protect against service outages. Storage and networking are the walls that help support your virtualization infrastructure.
Windows Server 2012 R2 Licensing