I’m not sure what cruise line you were on, but on every cruise line I’ve traveled on, you can buy booze in the duty-free store, but you can’t take possesion of it until the night before final disembarkation. To prevent people from doing what you described, mixin’ their own.
Didn’t know that. Of course, I was crew, so that might have made a difference. I sure thought I saw folks buying booze and cartons of smokes and taking it/them out of the shop, maybe I’m mistaken, it’s been a few years (2005) I know >I< did, plenty.