How do you extend the life of formula milk? I understand that you can only keep it for a max of 1 month.

Stick to the one-month guideline recommended by formula companies. Unlike other baby food that can be frozen, it's not recommended to freeze formula. The enfamil website says this: “Freezing of any Enfamil formula is NOT recommended. Freezing infant formula can lead to physical property changes like fat separation, which may prove difficult for sensitive infants to digest. Freezing will not extend the expiration date of the formula.” “Freezing of our products may cause loss of desirable appearance and functionality (though not nutrition), and is not recommended."