The food production license is valid for 3 years. The validity period of production licenses for different foods shall be stipulated by the corresponding normative documents.

Look at the materials you applied for. It should say deadline.

Besides,

Within 6 months before the expiration of the food production license, the enterprise shall apply for extension to the quality and technical supervision department that originally accepted the application for food production license. The quality and technical supervision department shall review and renew the certificate in accordance with the prescribed application procedures.