This very much depends on one’s personal style of vaping and what they are using CBD for. Each PhenoPen cartridge contains 500 mg of pure hemp extract with 300mg of CBD and can last anything from a week to a month. Each Phenopen cartridge provides approximately 300 small-to-medium puffs (dependant on a number of factors). 

Here is a rough guide depending on usage: 

Beginner: 300 puffs per cartridge total - 5 puffs per day = 60 days 

Intermediate: 300 puffs per cartridge total - 10 puffs per day = 30 days 

Advanced: 300 puffs per cartridge total - 20 puffs per day = 15 days