The Nemasys Beneficial Nematodes (250 million nematodes) will arrive to you with an expiration date on the container so you know when to use it within. As long as you follow the instructions to store the container completely sealed at 40 degrees Fahrenheit until ready to be used, they will stay stable and alive at least until the expiration date. We have technical sheets and detailed storage and use instructions on the product page for this item, and you can scroll down the product page to see the information and details.