To keep your animal water purification drops fresh and effective, store both bottles in a cool, dark place. Do not allow them sit in direct sunlight or near sources of heat.
Your set is best-kept in a pantry or in the refrigerator with the bottle cap securely fixed.
For longer term storage, it is best practice (most ideal) to store each bottle without the droppers in-place. The cap that is included on each bottle at the time of delivery ensures that the contents are not exposed to air.