Store dried mushrooms sealed, cool, dry, and away from sunlight. Follow the actual product’s date and storage directions rather than assuming dried means indefinitely stable.
Opening and decanting
Use dry hands and utensils and reseal promptly. If moving the contents to a jar, retain species, lot, date, and storage details. A decorative container that loses the original label also loses information you may need for a quality question or a repeat purchase.
A humid-climate pantry
Choose a cupboard away from a stove, sink, or sunny window. Avoid exposing cold contents to humid air and then sealing condensation inside. Keep a small working portion separate if repeated kitchen use would otherwise expose the main package to steam.
When to stop using it
Unexpected dampness, mold, pests, or an unusual odor is a reason to discard or contact the supplier. Re-drying compromised material does not reliably make it safe. A best-before date assumes correct handling; it is not a guarantee after moisture damage or an opened package stored poorly.