SETAPP is a new way to buy software for your Mac. You pay $9.99 per month, and get access to more than 70 curated Mac apps, and Studies is now one of the apps available to SETAPP customers. You don't have to pay for upgrades, and there are no other costs. A flat rate subscription gives you full usage of the apps, and they will be automatically kept up-to-date. There is a one month free trial, so give it a try!