Fresh Keeper / Deadline for eating

Though every kinds of food have a "deadline" for eating, people usually ignore them until they have a stinky smell. However, people can hardly find some food which has expired when the food doesn’t have significant changes after they have expired or the cover paper of the food has already gone. Thus, people might eat the expired food and it would hurt people's health.
It is a system of keeping food fresh. After the food is opened, it can be put into a container which has equipped the system and you can set the "fresh date " of the food. People don't need to be careful about the date all the time.