I was using the free trial offer and naively left the service active.
I was thinking that the charges would be based on user's access.
Finally I did stop the service thinking that this would have stopped the charges.
Instead I got a message saying that you must completely delete the service to stop any charge.
Think about this like renting actual storage space.
It does not matter if you are storing junk that you do not use.
You are still going to be charged, unless you relinquish the space and related service.
I will contact customer support for further clarifications.