I've been using Corte Clean for 12 years to clean my Trex deck, spring and fall, in Michigan. When I'm done, it looks clean and new. Last year, 2020, I went to Northville Lumber, and they were sold out, so I ordered online. I used one back in the fall of 2020, with the usual results and was going to use the second one this spring, but it was always raining so the opportunity did not materialize. The package I just used says best if used by 051521. For the past 11 years, I stored them in the climate controlled basement. This past year I stored it in the garage, which isn't climate controlled. The results were disappointing, it did not clean well at all, even after two applications. I used up the entire package doing a third time and it still looks bad- better, but not clean. Lesson learned. I just ordered more fresh Corte Clean.