Apple Music officially launched a couple of weeks ago with iOS 8.4 and with it came a free three month trial with every account.
However, like any subscription you sign up for (magazines in Newsstand, Netflix, Spotify, etc), Apple will automatically start charging the payment method on your Apple ID ($9.99/individual plan or $14.99/family plan) when the trial period ends.
Of course, turning off auto-renewal is hidden deep in settings. You can turn the auto-renewal for Apple Music or any other subscription you have by following these steps:
1. Go to iTunes on your Mac.
2. Click on your account name on the upper right of iTunes
3. Select “Account Info”
4. Click on “Manage” next to Subscriptions
5. Click “Edit” next to Apple Music
6. Tick “Off” under Automatic Renewal
7. Click Done
If you do decide to keep Apple Music, then just follow these steps again later to turn auto-renewal back on.