Another key factor to consider—aside from organizational type and size—is which products and services you want to license. Different product families require different licensing models. For example, a desktop PC program, such as any Microsoft Office 2013 suite, requires a license for each device that is running the program. Customers can install any number of copies and any prior version on the device or on a network device.
A desktop PC operating system, such as the Windows 8.1 Pro operating system, requires a license for each device accessing the licensed product (locally and remotely), and only one copy can be installed on the device.
In Volume Licensing, the desktop PC operating system license is an “upgrade license.” You can acquire upgrade licenses only for devices for which you have already licensed a “qualifying operating system,” either preinstalled on a PC through a PC manufacturer or as full packaged product (FPP) from retail. The Product List shows the “qualifying operating systems” that qualify for an upgrade license and is available on the Volume Licensing website at www.microsoft.com/licensing/products/products.aspx.
Meanwhile, most server products require a license for each running instance of the server software that you run on a server—whether in a physical or virtual operating system environment (OSE). However, some products provide broader use rights. For example, a Windows Server 2012 R2 Standard edition operating system license permits a running instance in up to two virtual operating system environments, plus one host instance on the physical device solely to manage the virtual instances at a time on the licensed server. With some products, such as Windows Server 2012 R2 Datacenter edition, any number of instances can run simultaneously. Both Windows Server 2012 R2 Standard and Datacenter editions require that each physical processor be licensed on the licensed server in addition to every virtual instance running at any given time on Windows Server 2012 R2 Standard.