Raw sunflower seeds will last for 2 to 3 months if kept in a cool, dry place in airtight containers. Roasted seeds in the shell will last 4 to 5 months in the pantry or refrigerator and up to 1 year in the freezer. If the seeds have been shelled after roasting, they will last for 3 to 4 months in the pantry or refrigerator and up to 1 year in the freezer.