I always freeze milk in the gallon jug that it comes in from the store. You do need to break the seal and pour off about 1/2 of a cup before freezing. Liquids expand when they freeze and the top of the plastic jug can split if you don’t pour a little off. I havekept it a month or more. If you use a deep freezer that reaches temps below zero degrees, you could easily keep itmonths.