Right. If all you are using your master DAW for is to host VEP VST Instrument and not actual VSTs via the VEP Server. Basically, any where you want to run VEP Server to host VSTs will need a vienna license on a eLicenser USB key. Basically...evey physical computer.
I run VEP Server on my master daw as a "Local Host". I like to host effects plugins that way for things like send effects such as Reverb. It operates outside the memory space of the DAW and offers fantastic performance benefits.
So, if you are running 3 computers total, you need a elicenser USB key and the VEP license. Aka- 3 keys. I run Cubase and already had a steinberg usb dongle, so I only needed to buy 2 more to make my 3 computers work together in a Master/2 slaves config.
The VEPro license are sold in 3 packs. So, if you are a pro "like some here" and have a giant setup of 30+ slave computers, you will need 30 keys and licenses.
If you share what you are trying to do, I am sure Paul, or one of us, will guide you for what is needed to get setup.
Vienna Ensemble Pro is an awesome product!