The ten other devices you can manage with a single iTunes account will all have access to your iTunes purchases through the cloud. Unfortunately this does not make for a total of fifteen devices, as authorized computers can also have access to iTunes in the Cloud and therefore will count against the ten devices.
The good news is that ‘dumb’ devices like traditional iPods (not iPod Touches) and even the Apple TV (which cannot download content locally) do not appear to be included in the count of ten. That’s also the case for any AirPlay enabled appliance or speaker you have that you want to use. You can have any number of these devices accessing your purchased content.
Managing devices and computers
The only way you can get to some of the iTunes’ account management features is via iTunes on either OS X or Windows. While you can add and remove each iOS device individually from an associated iTunes account, you cannot access a list of other associated devices from an iOS device. Hopefully this will change in future iOS releases as more and more people forgo computers altogether in favor of an iPad-only existence.
To access the account management features from within iTunes, first click on the iTunes Store button. From the “Home” page of the store, you will see an “Account” link listed under Account Links on the right side of the screen. Clicking on it will take you directly to a page that lists how many of the five computer authorizations there are on the account as well as how many of the ten devices are associated with the account.
While you can remove individual devices from your list of ten iTunes in the Cloud devices, you cannot perform the same task on your five authorized computers. You will only be able to access this feature once you have reached the maximum number of five authorizations. Often times having repairs done or even reinstalling the operating system can require you to re-authorize a computer a second time. Some times you get lucky and iTunes will recognize that the computer has already been authorized and not count it a second time. It is therefore always a good idea to deauthorize a computer before performing such tasks, if you can.
Multiple Apple IDs on each device
Something to keep in mind before you start associating multiple accounts on a single device is that your iTunes account is actually an Apple ID. Problems can arise when you have more than one Apple ID since Apple IDs cannot be merged. This problem is amplified when you start associating your Apple ID with online purchases. In the case of iTunes, those purchases remain forever bound to one Apple ID. Sometimes quite literally in the form of Digital Rights Management (DRM) as is still the case with most books, movies and of course apps.
On both OS X and Windows this is done by selecting the “Authorize this Computer” menu item from the Store menu. This is where you add and remove your computer from the list of five authorized computers. Just keep in mind that it is when you sign in to the iTunes store on either OS X and Windows that your computer will be added to the list of ten “iTunes in the Cloud” devices. Only after signing in will you be able to download prior purchases.
Control iTunes spending
One technique to control iTunes spending is to set up an account without a credit card. This will not work once all of your devices are configured to use the same iTunes account you use to make purchases. If that is the case you will have to look at restricting the ability to make purchases on a device by device basis.
On iOS this means that you will need to enable restrictions which are found within the General section of the Settings app. Here you will be able to turn off in app purchases, disable the ability to install and delete apps, and even remove access to the iTunes and iBooks stores entirely from the device. For OS X and Windows, the iTunes parental controls are accessible from with the apps preferences menu.
There are some features of an iCloud account that are useful even if you don’t want to use it for email. Photo Streams, Keychain Passwords, Safari Bookmarks and iOS Backups are such services but they are handled on a device by device basis. On OS X on the other hand is limited to one per logged in user account.
Another iCloud service that is more app based is the ability to sync data between devices. The data is bound to a user account and accessed exclusively from within the app. What is fortunate is that you can actually store an app’s data in iCloud using a different Apple ID than the one that was used to purchase the app. This allows one to manage app purchases with one iTunes account, and the data used by the app with a different iCloud account.