At room temperature should be consumed with in 3-4 hrs . Or else can refrigerated for 2-3 days but better to use as early as possible to avoid risk of contamination

If your baby did not finish the bottle, the leftover breast milk can still be used within 2 hours after the baby is finished feeding. After 2 hours, leftover breast milk should be discarded. Use the expressed milk within 4hrs if stored at 25degree or cooler.If u store milk in refrigerator at 4degree or cooler then u can use for 2-3 days.