getIntroductoryPeriod
ISO-8601 duration of one introductory cycle (e.g. "P1M").
Return
Intro period string, or null when there is no intro offer.
Since
4.4.0
Parameters
productId
Subscription product id.
ISO-8601 duration of one introductory cycle (e.g. "P1M").
Intro period string, or null when there is no intro offer.
4.4.0
Subscription product id.