AppSubscription::change() changes price, unit, name, description or
discount of a running subscription, prorated right away (APPLY_NOW) or
from the next period on (APPLY_PERIOD_END, shown as scheduled_change);
cancelScheduledChange() drops a scheduled one. Adds the
subscription.updated event type and documents proration_not_possible
and credit_exceeds_bill.
discount (label, percent_off or amount_off, duration once, repeating or
forever) when creating subscriptions and per subscription of checkout
sessions, the discount field on subscriptions and the
subscription.discount_ended event type.
trial_days, trial_ends_at and trial_once when creating subscriptions (app and
user token) and per subscription of checkout sessions. isTrial() on
subscriptions, the subscription.trial_will_end event type, and the
trial_already_used error code in the docs.
Maurice Preuß
