You may wish to contact Sandoz/Zoecon directly for advise on shelf life.
Apparently, the shelf life is quite long providing the strips have been kept
in a cool, dry place and away from sunlight. The active ingredient seems
particularly sensitive to UV.
Paul van Westendorp [log in to unmask]
Provincial Apiculturist
BC Ministry of Agriculture,
Fisheries & Food
Surrey, BC, CANADA
V3S 4P9