There is more misinformation on this thread than on any other I have ever seen. It's all over the place
I am reminded of Yogi Berra's famous question when he went over to the Mets. "Don't anyone here know how to play this game?" The policies that exist now, on all lines, that do not allow you to bring more than a bottle or two of wine aboard have little to do with customs or what country you board in. They have to do with the simple fact that cruise lines lose money by allowing passengers to bring their own booze on board.
Thus the birth of the industry-wide, misguided policies preventing us from doing so. You would think that spending thousands of dollars on a cruise would entitle you to the privilege of mixing your own drinks, and drinking your own wine (In case quantities if you prefer.) You would be wrong. You haven't spent enough money yet, and the powers that be in the industry have decided that they want you to drink their
booze not your own.
So unless you find a sympathetic employee who will look the other way, chances are your favorite scotch or your case of Cab '03, will be taken, and returned to you upon disembarkation.
Some lines have a program where they will (for a very hefty price) have a bottle of your favorite beverage placed in your stateroom as a sailaway gift. We did this on a HAL 30 day cruise with a nice bottle of tequila. I then sneaked a liter of Cointreau on in a plastic water bottle and we had margaritas on our verandah every evening before dinner. delightful, until the tequila ran out. Saved a bundle. So I imagine they've found a way to negate even that policy by now.