Activates a subscription.
The Subscription Activation call does not require a content body. This action will set the Subscription status to Active, which, in most cases, will generate an invoice and, depending on the customer's billing options, apply a charge and initiate a collection attempt against the Customer's payment method. The Subscription will activate regardless of whether the collection attempt succeeds or fails, so you should review the invoices to ensure payment was successful. This call returns the Subscription you have activated, so you can verify that the status field is set to Active. This action can only be performed on Subscriptions with a status of Draft or Provisioning. In Stax Bill, each Subscription is attached to a Billing Period, which defines the start and end of the billing cycle and the duration (e.g., one month, starting on the 1st of January, or 1 Year, starting on the 4th of May). Stax Bill allows a Customer to have multiple Billing Periods, meaning different Subscriptions can have different start and end dates (e.g., one Subscription starting on the 4th of the month, another on the 9th, etc.). You can define the Billing Period that the Subscription should align to when you perform this call by passing in the appropriate fields in the call body.