Store-bought eggnog potentially keeps for up to one year in the freezer if it is frozen before being opened and before its expiration date or best-by date passes. The Anderson Erickson Dairy recommends thawing frozen eggnog in the refrigerator and using it promptly.
It is best to freeze eggnog cartons upright and then transfer cartons of frozen eggnog to heavy plastic freezer storage bags. Eggnog that is frozen for months and then thawed may have off flavors. There is also the risk of separation during the thawing process. A quick shake of the carton or mixing the eggnog in a blender remedies this issue.
Off-season serving suggestions include eggnog smoothies in the summer or an iced eggnog latte.