Alcoholic beverages with 24% alcohol or less are not subject to limitations in checked bags. Mini bottles of alcohol in carry-on must be able to comfortably fit into a single quart-sized bag. For more information, see FAA regulation: 49 CFR 175.10(a)(4).
Only alcoholic beverages served by a flight attendant may be consumed on board. Beer and wine are available for purchase in United Economy only on select domestic flights.