"How long can the cartridge keep if you don’t use it often? Also, how many puffs can you get one from cartridge?"
According to a Ryan, a media assistant w/ Bloom Farms, cartridges last anywhere from 6 to 9 months then the quality starts to deteriorate. If you store catridges in a cool, dry place, it extends their shelf life. You can read his answer here: https://www.hellomd.com/answers/58518d58de3db80008256b6c/do-your-oil-cartridges-have-a-shelf-life
I don’t have a Bloom Farms cartridge but many of my cartridges are 1+ years old and they are still going strong. Just take care of them and clean all your instruments with rubbing alcohol.