We think Impossible™ Beef Made From Plants tastes best when served hot, immediately after being cooked. That said, you can feel comfortable storing and reheating it in the way you would other leftovers that contain minced beef, as Impossible Beef poses no unique food safety concerns.
Keep in mind that the length of time any leftovers (not just our products) are safe to eat is largely dependent on how they were handled before, during, and after cooking, so we encourage you to use your best judgement based on the way the leftovers look and smell.