Usage-based charges let your app charge a variable monthly fee. Your app can charge fees based on a number of actions or conditions, such as the number of products fulfilled per month or the number of orders processed by your app.
To create a usage-based charge, you must first create and activate a Recurring Application Charge. This recurring application charge must include a
capped_amount, which is the maximum dollar amount that your app can charge in a 30-day billing cycle, as well as
terms to describe the billing conditions.
Every UsageCharge is a child of a RecurringApplicationCharge resource. After you have created and activated a RecurringApplicationCharge that includes the necessary parameters, you can create Usage Charges associated with this particular RecurringApplicationCharge.
If you want to increase the
capped_amount during a merchant's billing cycle with your app, then send a request to Shopify that specifies the increased amount. For example, to increase the
capped_amount to 200 dollars, you would issue the following call:
The response from Shopify will include the
update_capped_amount_url parameter — you must redirect the merchant to this URL, where they can approve the increased amount. Until the merchant approves the increase, the
capped_amount will remain at its previous value.