cheese rennet
Probably not. Rennet doesn’t  go bad  so much as it loses its ability to coagulate milk after about 1 year. You can still try it, but you will need to use more and be willing to possibly sacrifice your batch. It it’s been more than 1 year, you will want to get some fresh rennet.

Cheese Making Glossary & Terms

Acid A descriptive term for cheese with a pleasant tang and sourish flavor due to a concentration of acid. By contrast, a cheese with sharp or biting, sour taste indicates an excessive concentration of acid which is a defect. Aged Generally a cheese that has been cured longer than six months. Aged cheeses are characterized
Below is a list of the most common issues and solutions for cheese making.