Windows Server 2012 Foundation
You can use Windows Server 2012 Foundation in either Active Directory® or workgroup environments to create up to 15 user accounts that can access and use the server software. Each user account permits one user, using any device, to access and use your server software with no client access licenses (CALs) required. In the Windows Server 2012 Foundation operating system, you will receive a warning message if you exceed the fifteen-user limit.