Boveda® packs can last between 6 and 10 months before needing replacement. It's lifespan may be increased by minimizing exposure to air. Once the humidity pack begins turning hard, the RH will begin to fall and this will signal the need for replacement.
The smaller 8g packs work best in our airtight 1/2oz jars and the 4g packs work great in the airtight 1/4oz jars. These smaller packs are calibrated to maintain 58% RH, which is perfect for maintaining flavor. Vape enthusiasts will prefer this ratio.