Actually, one can install RDSH on Windows Server 2012 in a Workgroup environment.
This configuration is appropriate when there is only one server on the network and it will provide desktop sessions to users based on the number of Remote Desktop Services client access license (RDS CALs) installed on the server, but will not provide access to RemoteApp programs or the RDWeb site.
You should install two RDS roles:
- Remote Desktop Licensing
- Remote Desktop Session Host.
Then install RDS CALs (either per user or per device).
The last step would be to configure the Remote Desktop Session Host role to use the local Remote Desktop Licensing server.
Guidelines for installing the Remote Desktop Session Host role service on a computer running Windows Server 2012 without the Remote Desktop Connection Broker role service: