Update subscription payment method

Payment Method Update Process:

• Fetch Latest Payment: Retrieves customer’s current default payment method from Shopify
• Update Contract: Associates new payment method with subscription contract
• Validate Payment: Ensures payment method is valid and active
• Sync Changes: Updates payment instrument in subscription billing system

Key Features:

• Automatic Sync: Pulls latest payment method from Shopify customer record
• Payment Validation: Verifies new payment method is usable for billing
• Contract Update: Updates Shopify subscription contract with new payment
• Failed Billing Recovery: Useful for updating payment after billing failures

Use Cases:

• Customer updates credit card and wants to apply to existing subscription
• Recover from failed billing by allowing payment method update
• Sync payment methods in customer portal workflows
• Update expired or invalid payment methods
• Switch between multiple saved payment methods
• Integration with custom payment update flows

Important Notes:

• Customer must have a default payment method in Shopify
• Payment method must be valid and not expired
• Updates are reflected immediately for future billing
• Does not retry failed billing attempts automatically

Authentication: Requires API key authentication via X-API-Key header or api_key parameter