Mobile Game Backend and Cost


I am currently developing a mobile game and after some research, I decided to use PlayFab as a backend. PlayFab absolutely provides all features I need! The features I need for my game is to have a login, save scores, save modifications of the player’s characters and handle IAPs (incl. virtual currencies).

FYI: I have never launched a game before that requires a server.

I apologize if this thought is stupid, however let’s imagine my game went unexpectedly viral, could I get a hugh bill from Microsoft to pay for the requests? I know it’s free up to 100k users and 150k requests, but what happens when I suddenly surpass those limits?

To manage the “risk”, a friend recommended me to write my own backend, let’s say with cakephp or laravel, and put it on my own webserver which cost 3€ per month.

Generally, I have no problem to go either way. I only read, if you want to work with people’s money, you shouldn’t cheap out on services (what makes sense to me!). This led me back to use PlayFab again.

What would you guys do? Would you make your own backend or use a service? How do you calculate the cost or “manage risks”?
I would really appreciate if you could give me any recommendations and/or tell me your experiences!