A Render node license is a license that may be used on a render node computer only, where the host application (3ds Max or Cinema 4D) is running in command line mode with no user interface visible. For example, this is used when rendering using Corona's Distributed Rendering or Autodesk Backburner in 3ds Max, or when using Team Render in Cinema 4D.
A Render node license does not allow a user to open the host software and use the Corona GUI, and as the name suggests only allows that machine to render.
Please note that any Render node license will work with either 3ds Max or Cinema 4D - you do not need unique versions of the Render nodes for each host software.