"schedule": {
  "interval": 1,
  "interval_unit": "month",
  "max_interval": 12,
  "current_interval": 2,
  "start_time": "2019-05-29 09:11:01",
  "previous_execution_at": "2019-05-29 09:11:01",
  "next_execution_at": "2019-06-29 09:11:01"
}

JSON Attribute	Description	Type
interval	Subscription interval specified by you.	Integer
interval_unit	Unit of time interval. Note: Supports `month`, `week`, `day`.	String
max_interval	Maximum interval of subscription. Subscription ends after the maximum interval is reached.	Integer
current_interval	Current interval of subscription / count of charge at current time.	Integer
start_time	Timestamp of subscription in `yyyy-MM-dd HH:mm:ss` format. Time Zone: GMT+7 .	String
previous_execution_at	Timestamp of last succeeded charge in `yyyy-MM-dd HH:mm:ss` format. Time Zone: GMT+7. Note: On create subscription, timestamp value will be the same as `start_time`, but if `start_time` has not passed yet, the value will be null.	String
next_execution_at	Timestamp of next scheduled charge in `yyyy-MM-dd HH:mm:ss` format. Time Zone: GMT+7.	String