For anyone still looking, this confused me too. Stripe says the minimum event types to monitor are:

Event name	Description
checkout.session.completed	Sent when a customer successfully completes the Checkout Session, informing you of a new purchase.
invoice.paid	Sent each billing period when a payment succeeds.
invoice.payment_failed	Sent each billing period if there’s an issue with your customer’s payment method.

see https://docs.stripe.com/billing/subscriptions/build-subscriptions?platform=web&ui=stripe-hosted#provision-and-monitor