I have not yet decided what the best way to do this is, i.e. whether I should publish the source code for people to set up on their own server or if I should just allow theatres to set up private databases on my server.
My choice would be to publish the source. If you host it and it becomes too popular, cost of hosting may become non-trivial to you. Also, as a user, I would want to have control of the data that I put so much work into creating - at the very least you should provide a means for users to download a dump of the database for backup. With a published source, users can also customize to their specific needs. Of course there is no reason that you can't publish the source and provide a hosted database side-by-side to let users choose. I would explicitly reserve the right to change the terms of the hosted database, but make it clear that users would always be able to move to their own server.