Paid for Applications; Activation Codes

I don't see any API stuff for supporting activation codes and payment stuff.

Is there any conventions to follow here?
I naively kind of thought payment and paid for applications would be supported via the Garmin Connect IQ store.

Note I have not gone through the process of uploading an app to the store yet so don't now if this functionality is handled then.

How do people go about getting paid for downloaded apps?