Egg protein powder can last for approximately 12-24 months if stored properly in a cool, dry place and away from direct sunlight. It's recommended to keep the container sealed to maintain freshness and prevent contamination. Refrigeration is not necessary or recommended. Storing in a refrigerator can cause condensation to form which can cause your protein powder to spoil. Before using, it's important to check for any signs of spoilage or off-odors, which could indicate the powder has gone bad and should not be consumed.