Yes, you probably should do this - surprise billing will get you angry didn't-really-want-to-be customers and bad PR. A nearly-zero-effort way to do this is to

Yes, you probably should do this - surprise billing will get you angry didn't-really-want-to-be customers and bad PR. A nearly-zero-effort way to do this is to listen for the customer.subscription.trial_will_end webhook from Stripe - they'll send it to your app 3 days before the trial ends.