Out of the box Windows comes with 2 "licenses" for administrators to be able
to remotely administer servers using RDP. If you require more then 2
licenses then you will have to install Terminal Service and buy additional
Terminal Server licenses (e.g. 5 licenses) for your 5 connections.

There's two terminal service "modes"

Remote Administration (which is hard limited to two users)

and

Terminal Services (which you have to license for)

If you go into add/remove programs, then go to windows components, you can
switch modes.