This is from Royal's website:
Alcoholic Beverages (Note: On boarding day, each stateroom may bring up to two 750 ml bottles of wine or champagne. Guests who purchase alcohol bottles onboard, in a port-of-call, or bring more than the two permitted bottles on boarding day, will have their items safely stored by the ship. These bottles will be returned on the last day onboard for enjoyment once home. Alcoholic beverages seized on embarkation day will not be returned.
Guests may also bring non-alcoholic beverages as carry-on items on boarding day. Non-alcoholic beverages may not exceed 12 standard (17 oz.) cans, bottles or cartons per stateroom. Milk and distilled water brought on for infant, medical, or dietary use are permitted.