The shelf life of feta cheese in the fridge depends on the type (feta cheese blocks or crumbles) and whether it has been opened or not. Feta cheese blocks in an unopened package last about 2-3 months in the fridge. Feta cheese crumbles do not last quite that long because they are not packed in brine, but they should be good up to a week past the labeled date. If opened, both types of feta will last up to 5-7 days in the fridge. Only if you add brine to them, they should be good for about a month.