Right, only one person can be using the license at any given time (in a "live" sense of being inside a full version of 3ds Max or C4D and working in it - the render nodes give you 3 other machines that can use the same license for network rendering, with a Backburner Client for Max or C4D Client for C4D). The same main license can be used on any machine, so long as it is only active on one machine at once.