We haven't had any details yet...
It really doesn't tell anything.
Look at the station model in the X-series. Stations have an upkeep to maintain there as well, but if you setup your market smart, the thing becomes functional for its environment and it will start paying for its own. Is that really so hard to imagine it might be something like this?
If you add stations to this game 24/7, you might want the things to become an addition to the environment, especially when it is getting wired to things like the BGS for instance. Or if it used to undermine the environment by starting a market with ridiculous prices, you are going to have to work for it, just like it is now. If you gonna dump the thing somewhere and forget about it what's the point of it to be there, from a functional point of view.
From a technical perspective, Frontier needs to keep track of the carriers, where they are, what they do, what the traffic does, how it influences the environment. Allowing stuff to be added and never to be removed is a resource leak de facto.
You might even get your money back. We simply know nothing at this point...