How do subscriptions work?
You define the recurring price as line items with a monthly or yearly interval. The first charge is confirmed in the browser with Stripe Elements, which also saves the card; Forte then re-charges it automatically each cycle, and every renewal is recorded as an ordinary payment so your existing triggers keep working.
If a renewal fails, the subscription goes PAST_DUE and Forte retries over a grace period before cancelling — updating the card retries immediately.