You need to have few different types of bags.
You should not use the plastic bags but if you are selling any type of roasted beans, you need bag that would release gas or you need let it sit for at least 3-4 days after the roasting.
The Vacuum sealed bags will last much longer and some are being sold for 6 months after the roasting. I would not buy those but they are being sold.
I believe roasted beans last about a month and after about 2-3 weeks you are compromising the quality...
good luck