I was at Lodi Wine Labs buying Allegro yeast yesterday and had to buy 500gm. I got to talking with the head guy there about storage. I said flat out that it would be good at least 3 more harvests and likely longer, but the interesting thing he said, was not to freeze it. He said that vacuum sealed in the refrigerator was ideal, but he specifically said without prompting to avoid the freezer. Just thought I'd put that out there to add to the collective wisdom.