There's no such thing as "all-you-can-drink"
Cruises don't really position themselves as "all-inclusive" because they are NOT; while most cruise lines include food and some non-alcoholic beverages in the fare, they NEVER include booze. In fact, alcohol is one of those areas where cruise lines make a huge profit, so expect standard restaurant pricing.
Some lines do offer ALMOST all-you-can-drink packages but there is, again, a lot of fine print attached; some limit the selections, some charge more for premium packages, some automatically add a 15-18 percent service charge, some are only available during meal times, some cut you off at 15 drinks, and most do not include mini bar or room service purchases. For most of the major lines, expect to pay $45-$70 per person per day for quasi-bottomless booze.
Also, if you think you'll just be "savvy" and BYOOB (bring your own on board), think again; this is not their first high-seas rodeo and you are not the first person who thought of this brilliant idea. Bags are scanned when you board and liquor is confiscated (although there is sometimes a two-bottle allowance per room, but with a high corkage fee), including anything bought on an excursion in a foreign port.