Hi Soap,
Vienna Ensemble PRO is a HOST for your plug-ins. It requires a license on a ViennaKey to run (on each computer you want to use it).
Your plug-ins require licenses as well - but that has nothing to do with your VE PRO license.
Still, licenses have to be available on the computer you want to use your plug-ins on (be it with VE PRO or with your sequencer).
So, for Kontakt or Spectrasonics, if you want to run these plug-ins on multiple computers, you will need multiple licenses.
Does that help?
Best,
Paul