Running a server, you must pay a firme to host your server.
That is called a Dedicate.
The Dedicate keps your server 24/24 .
Even now, the dedicate is payed and its or for testing or it stay there.
This is possibile to make
Another server for players, accesible from patcher.
I have also a server and i know what i'm taliking here
Since you have done some research, how much does a Dedicated Server, that can hold the traffic any Aeria game does, cost per month?
Also, as Treisha mentioned, there are other things that go together with "Server Hosting".
I dont know if Aeria has its own machines (according to the "coffee spilt over the Shaiya machine by a GM" blooper, could mean they have their own machines to host servers on), but if they do, it saves a lot of costs, but they still wont be able to host servers for free.
The Item Mall was an option to make it profitable, but it would be too much work for the GMs afterwards.