How can I check authorized computers using my iOS iPhone
How can I see what computers are hooked up to my iTunes or my iPhone 6 Plus
iPhone 6, iOS 9.3.5
Hi,
Check your device list to see where you're signed in
- Sign in to your Apple ID account page, then scroll to Devices.
- If you don’t see your devices right away, click View Details and answer your security questions.
Click any device name to view that device's information, such as the device model, serial number, and OS version. The information may vary depending on the device type.
Source found:
https://support.apple.com/en-gb/HT205064
Hope this helps