These are instructions on how to check the number of computers you've authorized in iTunes. Apple only allows you to authorize five computers to sync or play content that you download from the iTunes Store.
Step One
Launch iTunes from your dock.
Step Two
If you aren't already signed in, choose Sign In from the Account menu at the top of the screen.
Input your Apple ID email address and password then click Sign In.
Step Three
Choose View My Account... from the Account menu.
Step Four
You can find the number of authorized computers under your Apple ID Summary.
Computer Authorizations: 5 computers are authorized to play content purchased with this Apple ID.
Step One
Launch iTunes from your dock.
Step Two
If you aren't already signed in, choose Sign In from the Account menu at the top of the screen.
Input your Apple ID email address and password then click Sign In.
Step Three
Choose View My Account... from the Account menu.
Step Four
You can find the number of authorized computers under your Apple ID Summary.
Computer Authorizations: 5 computers are authorized to play content purchased with this Apple ID.