Once the foil sealed bag of formula is open:HiPP Milk Formulas have a storage life of 3 weeks.Holle Milk Formulas have a storage life of 2 weeks.Lebenswert Bio Milk Formulas have a storage life of 2 weeks.Due to environmental factors such as air, humidity, and temperature, which can impact its quality of freshness we recommend storing the opened formula in an airtight container to ensure short-term freshness. Store formulas in a cool, dry place (at room temperature) and not next to substances or foodstuffs with a sharp smell. Do not store in the refrigerator.