No, you don’t need an activated license for each computer you monitor.
It sounds like the terminology is confusing you, as it does many of us:
Client computers run Glasswire to monitors the other PCs which are called servers.
These GlassWire clients require activated GlassWire to enable remote monitoring of other computers.
With an Elite license you can have ten GlassWire client computers
Server computers provide the data to be monitored i.e. GlassWire allows itself to be monitored remotely and serve the GlassWire data to the client computer.
These servers can run either free or activated GlassWire.
An Elite license allows the monitoring of unlimited servers. But there will be a practical limit for how many servers a client can handle. The client computer will hit some limit in its ability to connection to all those computers and process all that data - I just haven’t heard of anybody hitting that limit.
You can check these details in the following page: