The shelf life of mac and cheese depends on whether it's homemade, store-bought, or prepared from a mix. Here are some general guidelines: 1. Homemade Mac and Cheese:    - If stored in an airtight container in the refrigerator, homemade mac and cheese typically remains safe to eat for about 3-5 days. 2. Store-Bought Packaged Mac and Cheese (Unopened):    - Unopened store-bought mac and cheese, whether it's in a box or a sealed pouch, can last for several months to a year or more past the "best by" or "use by" date. Check the packaging for specific guidance. 3. Store-Bought Packaged Mac and Cheese (Opened):    - Once opened, store-bought mac and cheese should be resealed and stored in an airtight container. It can remain safe for about 3-5 days in the refrigerator. 4. Prepared Mac and Cheese from a Restaurant or Deli:    - Leftover mac and cheese from a restaurant or deli should be stored in the refrigerator and consumed within 3-4 days. 5. Frozen Mac and Cheese:    - If properly stored in an airtight container or freezer bag, homemade or store-bought mac and cheese can be frozen for 2-3 months. It's important to label the container with the date to keep track of its freshness. Keep in mind that these are general guidelines, and the actual shelf life may vary depending on factors like temperature and storage conditions. Always use your best judgment, and if there are any signs of spoilage such as an off smell, mold, or unusual texture, it's best to discard the mac and cheese to ensure food safety.