That's a question with no answer. Depending on the bevel and condition of the edge, it could last forever. I have picked up Genco's over 100 years old that with some minor honing on a 8k or 12 k and stropping and it was ready to go. If stored correctly, you could pick it up in 10 years, strop it and have a really good shave. If you aren't going to use it, I suggest a fine machine oil coat the blade and pins. Then put it in the cloth sleeve. I found sewing machine oil does an amazing job and is easy to remove.