Defines how often are the subscription Purchases generated. Used together with subscription_period_units: to issue Purchases once a month, use "...period": 1 and "...period_units" == "months".

Variable number of days in a month is respected; e.g. if subscription has a period of 1 month, a client had its billing cycle activated on January 30 and there are 28 days in February that year - billing scheduled for February will happen on 28th.

Both fields are required when creating a BillingTemplate with is_subscription == true/editing a BillingTemplate with is_subscription == true as long as there aren't any launched subscribers; they are read-only otherwise, whether it's BillingTemplate's editing when there already are clients activated or if is_subscription == false.

Used to generate due on the Purchase objects generated. Used together with subscription_due_period_units: to set the final Purchase.due to a week after it's generated/invoice is sent, use "...period": 1 and "...period_units" == "weeks". Required if is_subscription == true`, read-only otherwise.

How many trial periods to give the client prior to starting his billing cycle. If billing period is 1 month and you set this value to 2, subscription will automatically adjust to giving your client 2 months without payments and then charging him for the 3rd month (when exactly depends on subscription_charge_period_end: 3 months after the subscriber was launched for false, 4 for true). "subscription_trial_periods": 0 disables this feature.

Required when creating a BillingTemplate with is_subscription == true/editing a BillingTemplate with is_subscription == true as long as there aren't any launched subscribers; read-only otherwise, whether it's BillingTemplate's editing when there already are clients activated or if is_subscription == false.