So let's say that I've finished programming a simple, indie MMO game similiar to Tibia.

I've got a stable server application that is ready to launch, i've got a tested bug-free working client application that is ready to play and the game's official website (ready to host) with payment system and client that is ready to download for free. Let's say none of them break copyright laws, and no matter how impossible it sounds, let's for now say it's true.

My game divides accounts into two groups - free and premium. If someone gets premium, he's granted access to all possible game features, that of course, need server authorisation to work properly. Let's say that the "premium account" can be bought on the website for a fixed money/month. Free accounts mean that everyone can actually play, but without paying, you get limited access. This is what the mentioned payment system will be for.

Well, I'm completely novice to these business entities issues, so in short: what, in terms of law, are steps from here to the state where my game earns money in a fully legal way ? Also, is there for example, something like verification if game gives the user what it actually offers when paying on its website ?

I live in Europe, if it changes something.