Android Question In App purchases / subscriptions

[iCAB]

Hi All

I have an app that allows the user to use some functions that cost us money to maintain (for example: firebase storage etc.. )
Heavier usage, costs more. So it will not be fair to charge a fixed subscription fee for all users.
I am wondering, if we can apply a credit system and if so are we violating any polices.

I will break this into 2 questions:
1. Are we allowed to have a credit/points system?
2. Are we allowed to issue credits for physical services outside the app.

Here is an example:
****************
1. User downloads the app, and gets X free credits

Consume credits
2. Say for every upload to Firebase the user consumes 10 credits
3. When the Credits go to 0, the user will be forced to purchase more credits (or earn credits by providing some services outside/inside the app )

Earn credits
4. Say for every service (physical service.. like a delivery etc.. ), the user earns 100 credits
5. Or for helping answer a question to another user, he gets 10 credits

Does anyone have experience with this?

Thanks
iCAB

 

[Erel]

https://developer.android.com/google/play/billing/billing_overview.html#products

I'm not a lawyer, I don't see any problem in the proposed usage.