The asterisk is probably a disclaimer about storage conditions. How you store them will affect how long they will keep. I would suppose you could store them in a manner that they would not last that long.
These alkaline cell batteries work by a chemical reaction. During storage, and use, the chemical reaction slowly eats up the battery internally, as the liquid component is acidic, until it will no longer make electricity. Car batteries work in much the same way, but use a liquid with dissimilar metals instead of a paste used in AAs, AAAs, etc. This is a rather simplified description, but suffices for what I need here.
Anyway, this reaction is slowed down in cooler climates, particularly with the cell batteries such as AAs, Ds, etc. This is why many people used to keep them in the refrigerator.