How is the finished application transferred from the coder to the customer?

Question

Android

Situation: I ordered to freelance to develop an application, how at the end of development and in what form (correct) is my order transferred? ( apk, pure source code) and already signed and generated with keys is given to me in the form of files? If I change the keys in the application at the same moment (but I won’t put it in the market yet), will everything be fine?
So far, I'm getting in the know, if there are guides or a specific tip, I'll be grateful!

Answer 1

You need the source code of the application (for further development), the certificate with which the application was signed and the data for the certificate (without it you will not be able to release the update in the future), and the assembled application (apk).