Each AROMA Dot could last up to three nights. Make sure to put each AROMA Dot back in its packaging after using it for the night, and take it out for your next slumber. The AROMA Dots should stay fresh as long as you seal the packaging tightly after each use.Upon opening of the packaging, your AROMA Dots could last for up to three months but to get the best quality of essential oil, we recommend using everything within a month.