It is important to keep apples in your refrigerator if you want them to last as long as possible and also to stay nice and crisp/crunchy. You will notice that when you keep apples out long enough, they start to become softer and eventually mushy on the inside. This is when they start to rot and you will want to keep this from happening as long as possible. Although you do not need to keep apples refrigerated in order to enjoy them when you get back home from the market, they are best kept in the coldest part of your refrigerator so that they will last as long as possible. Usually the best place to keep apples in your fridge is the vegetable crisper on the bottom which is able to keep fruits and vegetables fresh for a while so you will be able to keep enjoying them.