Billing API

Shopify Partner
2 0 0

I read the document regarding to the billing API and I hope some of you can give me a hand.

I want to build an app with recursive payment and have 7 days free trial.

I am confuse about the shopify billing process:

1. Is the billing function used before the installation of the app or after?

2a. If before, how can we POST /admin/recurring_application_charges.json without accessToken (I believed accessToken only available after app installed)

2b. If after, is that mean in client's shop page, this app will appears in the apps page but will not function until the billing process is complete?

3. What response determine whether the client had paid for the app?