For those of you with rancid butter problems--check with your food market. As with all food items butter should be sold by the date on the label. I have never had rancid butter.
Butter can be frozen. I do it often as I may go to the grocery store every 10-14 days. This works great when if you live alone and/or find butter on sale. Place the butter in a freezer bag, (Aren't Ziplocks great?) and put the date on the bag. You can take a stick out at a time if you like and keep it in the freezer for up to six months. Once thawed it is recommended to use it with in 30 days.