Sunscreens are good for only one year.
Most bottles of sunscreens don't list an expiration date on the tube. And many people are often told to throw their sunscreen away at the end of every season.
Unless indicated by an expiration date, a general rule of thumb is that sunscreens are stable for 3 years from the date of manufacture when stored at room temperature.
Tell people there's no need to throw out the sunscreen that they bought last summer. But explain that some sunscreen ingredients may degrade when exposed to heat. There's no guarantee that they offer the same protection after repeatedly being left out in the sun at the beach or in a hot car for long periods of time.