I just came across some instructions on how to store feta cheese, mentioning you can keep it for about 3 months in the fridge in a brine or milk bath:   Store the cheese in a brine or milk bath if you do not intend to use it for a long period of time. A milk bath will result in a creamier, softer taste, while brine will add depth to the cheese and retain its pleasant saltiness. To make brine, mix 1 lb. of kosher salt in 1 gallon of water.  Place the feta into an airtight container and cover it with the brine or milk.  Cover the container with a lid and store it in the refrigerator to keep it fresh for up to three months.   From: http://www.ehow.com/how_6496964_store-feta-cheese.html  A similar claim is stated here:  If you will not be consuming it immediately, store feta cheese in a brine or milk bath. The milk bath will reduce the saltiness and help keep the cheese moist and mild in flavor. Properly stored in brine or milk and refrigerated, feta cheese will last up to 3 months. Feta cheese is not a candidate for freezing. From: http://homecooking.about.com/od/cheeseinformation/a/fetatips.htm  I can believe the feta will keep that long in the brine, given the pound of salt that goes in. But I'm more skeptical about the milk bath. Wouldn't the milk spoil a lot sooner and affect the feta too? Or does enough salt leak out of the feta to act as a preservative for the milk as well? Or is the idea simply that you regularly replace the milk (though the instructions don't mention this)? Does anyone have any experience with this? 
I’m Greek and have eaten feta all my life. It is common practice for all Greek people to store their feta in milk once they bring it home from the shop, and in an airtight container, in the refrigerator. This does make the cheese creamier and less salty. It also preserves the cheese longer but definitely not as long as 3 months. You will be lucky to get 2 weeks maximum from this method. Feta cheese turns very quickly so it must be eaten as  soon as possible. It does not freeze well.  