How to transfer all rights to the iOS and Android application to the customer?

Question

Android

Good afternoon!
Written app for iOS and Android.
It is required to transfer the application and all rights to the customer.
What should the customer have for this in terms of legality? Developer certificate? Development licenses? What else? Where can I find detailed information?
Thanks in advance!

Answer 1

read articles like this
developer certificates are the tenth thing and have a very indirect relationship to the rights to the application

Answer 2

contract,
no one should have anything other than the contract (and the fact of transferring money, if the contract is monetary)