To use this cat food, simply open a tray by snapping it open. You can serve it directly to your cat. There's no need to heat it up, but you can if your cat prefers warm food. Make sure to check the expiration date on the packaging before serving. Store the unopened trays in a cool, dry place. Once opened, any uneaten food should be refrigerated and consumed within 24 hours to keep it fresh and safe for your cat.