Authorization of Devices

Just computers (up to five) can be authorized. Authorize or deauthorize your computer for iTunes Store purchases - Apple Support

If unknown or previous devices are (still) authorized, then you can Deauthorize all, and then re-authorize just the wanted ones.

• Authorized computers are different from ‘associated devices’ (roughly: computers + mobile devices). View and remove your associated devices for purchases - Apple Support
• Both of these are different from devices where you are signed in with your Apple ID account (computers + mobile devices + other personal devices). Check your Apple ID device list to see where you're signed in - Apple Support