If you read between the lines, the PolyQuat is very stable and not expected to degrade. It should probably last several, if not many, years (especially if kept in cool conditions that are not freezing). The "guarantee" is based on purchase date (there is a presumption of turnover and the "one year" number is a default, not something determined explicitly for this product) but in practice there shouldn't ever be a need for this. However, I doubt if anyone in the history of this pesticide has ever returned it to a store because it "went bad".

Richard