Storage of Maple Syrup You may keep unopened bottles of Crown Maple® syrup in your pantry up to the "best by" date printed on the bottle, avoiding exposure to high heat. All pure maple syrup must be refrigerated after opening, and will last for a year in the refrigerator. Maple syrup can also be kept in a freezer. It will not freeze solid and will keep indefinitely. Warming maple syrup before using will enhance the flavor.