From 2013 on, there will be some changes concerning under which circumstances one will have to pay:
Following the principle "one flat, one fee", each household will have to pay a license fee of €17.98 per month. It does not matter if the members of the household have a TV or a radio nor does it matter how many they have.
If you are living in a shared flat you will be lucky, because you will probably have to pay less then before.
The broadcasting services published a flyer with further information.
You can register with the public broadcasting services online. For membership cancellation you will have to send a letter.