Once upon a time, music purchased in Apple’s iTunes store was saddled with a DRM technology called “FairPlay.” It did just what you’d expect: keep unauthorized computers and devices from playing music purchased on the service. It’s gone from Apple’s music store now (but can still be found in eBooks and apps), but it’s still making waves: Apple is facing a $350 million anti-trust suit claiming the DRM was used to stifle market competition.