Ketchup that is not refrigerated will keep for around 1 month. Make sure the bottle is properly sealed. If you don’t think you’ll consume your bottle of ketchup that quickly, store it in the refrigerator. If refrigerated, ketchup can last for up to 1 year. You’ll know ketchup has gone bad if the bottle is leaking or bloated, it has a strange sour smell, it has mold, or it tastes bad.