Our mushroom extracts do not have an 'Expiration Date' but a 'Best Before' date.
The extract powder in the capsules only contains inert compounds which do not oxidize or react with each-other. They do not expire / lose their bioactive properties over time. The only thing is that due to the hygroscopic properties of these extracts they can solidify over time because they have absorbed moisture from their environment. The chances of this happening are minimised by packing the extract in capsules inside an airtight, sealed pouch.
If the moisture levels increase the potential for bacterial contamination also increases, which is why we still use a 'Best Before' date. We do not use large batches so the 'Best Before' date is usually ± 1½ year away or even 2½ years (Chaga only).