If you’re using an iPhone, then you’re probably used to the fact that by now iCloud is downloading all your different purchases to every device.
It’s a great feature and one that allows you to keep up to date without actually doing anything. But if you’re low on data, you can turn off automatic downloads if you don’t want them.
To do so, head to the Settings app on iOS, and then the “iTunes and App Stores” page. Then, turn automatic downloads “off” for both music and apps.