I did a "free trial" once about 40 years ago. Pretty sure the only way to stop the billing would have been to hunt them down and kill them
Alternatively I suppose you could move to a different address and leave no forwarding information.
So it only took our government 40 years to realize people are being scammed like this? Baloney, more likely it took them that long to figure out a way to get a cut of the profits. They'll probably just require a permit, same as with all the unsolicited junk mailings we receive in our mailboxes every day.