How long does peanut butter last? The shelf life of peanut butter depends on a variety of factors, such as the best before date, the preparation method and how it was stored. Fresh peanut butter is made of peanuts, that's it! But manufacturers will add oil, salt, sugar and/or other preservatives to their jars. Peanut butter is naturally high in fat which raises the "good" cholesterol levels, just beware of any added trans fats on the nutrition label of your specific brand. 
How to tell if Peanut Butter is bad, rotten or spoiled?
Sight is usually the most reliable way to tell if your peanut butter has gone bad. A common trait of bad peanut butter is a change in texture from soft and creamy to hard and dry. The color of the spread may also become darker and the pleasant aroma disappears. 
How to store Peanut Butter to extend its shelf life?
You can help peanut butter keep fresh longer by storing it in your fridge immediately after use, although processed peanut butter will be fine on the shelf as well. Once prepared (if homemade) or opened from the jar, it should be stored in a tightly closed container. The original container works great to keep moisture and other contaminants from touching the peanut butter.
Homemade and natural peanut butter should be kept in the refrigerator to last longer as they lack preservatives. Always use a clean utensil when using the product in order to avoid cross contamination.