It has to do with copyright law.
Who owns your digital downloads? (Hint: it's not you)
Steve Jobs once said, "People want to own their music." Someone better tell the folks who run the iTunes Store and its competitors. When you pay for a digital music track or album from an online service, you get a limited set of rights and you most assuredly don't own those downloads. Here's why that matters.
Who owns your digital downloads? (Hint: it's not you) | ZDNet
Props!
Amazon music :2.1 Rights Granted. Upon your payment of our fees for Digital Content, we grant you a non-exclusive, non-transferable right to use the Digital Content for your personal, non-commercial, entertainment use, subject to and in accordance with the Terms of Use. You may copy, store, transfer and burn the Digital Content only for your personal, non-commercial, entertainment use, subject to and in accordance with the Terms of Use.
Fact remains it's yours to do with as you will... Besides they still sell CD's once you own a physical copy of that said CD it's not like they can come into your house and take it away. The whole DRM thing is really Apple's game, that's why i stopped using them. especially now since that whole Icloud erase music fiasco.
If a label wants to sue you for playing the music at a party, they have a right to if your files come from one of these services. Even if they don't, by law you can still get sued for playing songs for profit. Most DJs are just lucky they aren't hot, but if someone wants to sue, they can. The proper way to do it, is to get a license from the labels of the artists who songs you play for the night, but that's time consuming, so a fixed fee is used sometimes. Places like large resteraunt chains where constant music is played, pay a license fee for every quarter.
I remember a few years ago, reading about some places charging DJs a fee to play songs. I think it was somewhere in Europe. They even confiscated laptops that had all the music, but wasn't licensed to use for profit. This will be normal soon, because with technology, playlists can be seen by anyone, and that means if you make a lot of money a night, artists who were played for a set, can get a piece of the money that was made for the night. Once a good set number is reached that will be paid to each song played, the game will forever be changed. Pioneer's rekordbox DJ software is doing it(publicly viewed playlists) RIGHT NOW!
Learning these laws can save you money, or cause you to be dead broke.
There are still ways to hustle these laws. For instance, you can record the streaming songs, then save the file without all the nonsense they add to show where the file originated. You can easily say you have the physical cds or found some other way to get the music. Technically they can't prove your songs came from services that block that way of use, so it would be hard to prove their case.
I know I'm reaching, but better be safe then sorry, especially when dealing with dikkhead of the law, AKA, LAWYERS!
