Here’s How to Create an Apple ID Recovery Key on iPhone

The Apple ID recovery key is a randomly generated 28-character code that you can use to help reset your password or regain access to your Apple ID. When you create one, the only way to reset your password is by using another device already signed in with your Apple ID or by entering your recovery key.
Apple ID Recovery Key
However, proceed with caution. If you lose your key and you don’t have another trusted device you can be permanently locked out of your Apple ID. Creating one of these keys disables the regular account recovery. You might want to give a copy of your recovery key to a family member, or keep copies in more than one place.

Open Settings.
Go to Your Name > Password & Security. Scroll down to find Account Recovery.
Tap the switch to enable it. You’ll be asked to enter your device passcode. Then, a recovery key will be generated for you. Write it down or save it in a password manager that you can access on non-Apple devices or on the web.
Confirm your Apple ID recovery key by entering it on the next screen.

 
I repeat, make sure you have a copy or two of your recovery key. Back in 2014, Owen Williams of TheNextWeb had a close call when he almost lost his key. In that situation there is very little that Apple Support can do for you, if they can even do anything at all.
Tags: Apple ID, iPhone, Security