Hi I'm going to be going on a Royal Caribbean Cruise (Explorer of the Seas, out of NJ) and I was going to buy a drink package but missed my cut off date to pre-reserve. I did hear somewhere though that if you pay for something like a package on board after the ship has set sail in international waters that you can avoid hefty taxes on already expensive packages. (I know some packages aren't available for purchase after the first day, but I heard that as long as it's in the first day, it's possible)

Can someone confirm or deny this please? We set sail soon.