If Apples are too firm or sour when purchased, leave out at room temperature to ripen for 1-3 days, and once ripen you can refrigerate in a plastic bag. Doing so will keep them fresh for 3-4 weeks.
Apples can keep up to 6 months or more if they can be stored in an area where the temperature is between 30-40 degrees with high humidity.
Freezer storage for Apples is similar to Peaches. Wash, peel, core and slice apples. Coat with a solution made of 1/2 teaspoon of ascorbic acid (found at a vitamin store) and 6 tablespoons of cold water to prevent darkening. Place in a covered airtight container or freezer bags.