There are 4 PROs (Performance Rights Organizations) in the US ASCAP, BMI, SESAC, and GMR for licensing. Each PRO represents a different catalog of composers and writers and in theory, you do not have to pay all four PROs, but you can't ever be sure that all songs you are playing have rights represented by just one of those. We strongly advise you to pay to all four (all subscribe to the GYM Radio, read below). One of the main reasons why they are 4 is that the anti-monopoly rules in the US are forbidding for only one company to collect all music fees.
Getting a license from all four PROs is not as easy as you might think. The ASCAP page doesn't even include a fitness facility as an option and the GMR registration link is just opening an email address. We have decided to collect the fees for all 4 PROs on your behalf so you don't have to deal with it. The 4 PROs fees are already included in the GYM Radio Pro subscription.
All the 4 PRO fees are included in the GYM Radio Pro subscription.
Using any of those services at your gym doesn't cover your licensing fees, even if you are using the premium versions. In fact, all of those services are for non-commercial use only and you shouldn't use them at your gym.
Please be aware, that this type of licensing can't be used for active fitness classes. It can be used only a "background music". You have to request a separated licensing where the licensing fees depend on the number of people and number of classes.