You should always select fresh organic apples when preparing baby food. Make sure you minimize cooking time to help preserve vitamins and nutrients in the apple.
You can always make more apple sauce and store them in a BPA-free container. Usually, apple sauce can store up to 3 days in a fridge and 2 months in a freezer.
Always check with your pediatrician before introducing new food to your baby and make sure they have no food allergies.