Hard-shell clams can be kept alive for up to seven days and soft-shell clams can be kept for up to four days with proper care. Once clams have died, they are not good for eating.
Clams are best when cooked live, so they must be kept alive until ready to prepare. Keeping clams alive requires ice and air. Cooks can fill the bottom of a cooler with ice and place the bag of clams on top of it. Cover the clams with a damp towel and keep the cooler in the refrigerator. Keeping the clams on ice helps to slow down their metabolism and keeps them alive longer. Clams must not be allowed to warm up or be placed in water. This can kill them. Clams are not to be buried under the ice. This could freeze them, and hinder access to air.
When ready to cook the clams, check each one to see if it smells like the ocean. If it does, then it is still good. Open clams are a bad sign. Gently squeeze any open clam to see if it closes up, meaning it is still alive. If it does not close, it is most likely dead and should be tossed.
Shucked clams can be kept in the fridge for up to four days and up to three months in the freezer. Cooked clams last up to three days in the refrigerator and up to three months in the freezer.