Kibble should be kept in air tight containers at all times. Even if preserved with chemicals, it is susceptible to decay because of the oily ingredients, especially those kibbles which contain grain meals. Synthetic mixed Tocopherols (Vit E) preservatives also break down in the presence of air, light and damp. Storing kibble in a garage, basement or place where cleaning products are kept is never a good practice.
Keeping kibble in plastic bins is a controversial alternate especially if the bin is never cleaned. This produces all manner of bacterium and fungus which your pet then ingests. Leaving the kibble in the original bag inside a plastic bin with an airtight seal is a good solution, but storing in glass is far preferable. Plastic really never comes clean. Additionally all feeding dishes should be cleaned before each meal especially if plastic or metal.
Buying a huge bag for one small animal might be cost effective, but it may become rancid before it is completely consumed. With proper storage; closing the bag and making sure the lid is tight, kibble will stay fresher and safer for your pet.