The basic Proton multiplayer plan
is free , but , very limited.
If you really wanna use multiplayer in your game
it will cost you a minimum of at least $95 extra or more.
It is a data driven model and the free one comes with
60 gig of traffic...if you need more....pay time !
It will also depend on what parts of the Proton SDK GG Max
decides to implement.
Here's all, the info...
https://www.photonengine.com/en-US/Realtime/pricing
UNIRD12B
Let\'s actually make something happen with this one !