Short answer: you can be legally liable — and it can be expensive. Playing unlicensed copyrighted music in a gym is treated as a public performance under U.S. law, and rights‑holders or Performing Rights Organizations (PROs) can demand licenses, back royalties, and sue for damages and fees. (bmi.com)

What can happen (typical consequences)

• You may receive a cease‑and‑desist letter or a demand for payment/audit from a PRO (ASCAP, BMI, SESAC, GMR) or the copyright owner. PROs actively license and enforce public performances. (bmi.com)
• Civil suits: copyright owners can sue in federal court for infringement. Remedies include injunctions (stop playing the music), payment of actual damages or statutory damages, attorney’s fees and court costs. Statutory damages range roughly from $750 to $30,000 per work, and can go up to $150,000 per work for willful infringement. (copyright.gov)
• Back‑owed license fees and audits: you can be required to pay fees for past unlicensed use (often calculated or negotiated by the PRO). (gov.texas.gov)
• Account/contract problems: using consumer streaming services (Spotify, Apple Music, etc.) in a commercial setting violates their terms and can lead to account termination — and they do not cover public‑performance rights. (support.spotify.com)
• (Rare) Criminal exposure: criminal penalties exist for willful infringement in commercial settings in extreme cases, though criminal prosecutions of small businesses are uncommon. (copyright.gov)

Special note about classes and recordings

• “Background” overhead music and “instructor‑led”/dance/fitness classes can be treated differently: some services or PRO licenses that cover background music explicitly exclude instructed exercise or dance classes — meaning you may need additional or different permissions for group classes. (soundsuit.fm)
• If you record or stream classes (post video or make them VOD), you generally need synchronization and master‑use rights as well as public‑performance rights — those are separate licenses and can be costly/hard to clear. (jdsupra.com)

What you should do (practical steps)

1. Stop using personal consumer streaming accounts for public playback immediately (they’re for personal use only). (support.spotify.com)
2. Contact the PROs (ASCAP, BMI, SESAC, GMR) and get the appropriate public performance licenses for your location(s). Fees vary by venue size, number of locations, type of use, and whether classes are instructed. (bmi.com)
3. Consider switching to a music service built for businesses/fitness (Pandora for Business, SoundtrackYourBrand, Rockbot, SoundMachine, Soundsuit, etc.) — some cover PRO performance rights for background music, though instructor/class exclusions may still apply. Check each service’s terms carefully. (sound-machine.com)
4. If you record/stream classes, plan to clear sync/master rights or use royalty‑free/appropriately licensed library music specifically cleared for video. (jdsupra.com)
5. Keep records (which tracks played, when, which service supplied them); if contacted by a PRO, prompt cooperation and switching to a licensed solution can reduce penalties. (gov.texas.gov)

If you’ve already been contacted or sued

• Don’t ignore notices. Consult an attorney experienced in copyright/music licensing right away. Early legal counsel can help respond, possibly negotiate reduced fees, or settle. The Copyright Claims Board (small‑claims route) may also be relevant for some disputes. (copyright.gov)

If you want, I can:

• list the contact pages for ASCAP/BMI/SESAC/GMR and business music services, or
• help you compare a few commercial fitness music providers and which types of rights they cover.

(References used above include ASCAP/BMI guidance, the U.S. Copyright Office on damages and remedies, PRO/business‑music providers, and legal articles on synchronization rights.) (bmi.com)