Fetches all payments (charges) made against a subscription's payment link. Each item is a standard charge object — the same shape returned by the Payments APIs and the subscription.succeeded / subscription.failed webhooks (see the Subscription Object). To attribute a payment to one of your users, read customer_details.email, or a key you stored in the payment link's custom_data (returned on the charge). Note: external_id is a separate top-level link parameter that the Create Payment Link API does not persist, so it is null for API-created links — use custom_data for attribution. The created_date can be used to decide whether a customer should remain on their plan or be downgraded.