Mine has lasted about 3 years, with perhaps another year to go. I multiply it before I eat it. It takes less than a tenth of a teaspoon to make a liter of (soya) yoghurt, and use that in four days. The packet is stored in the freezer, and the current sachet carefully sealed in the fridge. It seems as viable as when it was new. I don't know what difference VSL makes, because I use it continuously.