Every plan is free for 30 days, and Offers & Contracts bought on its own is free for 60 days. You add your card when you sign up, and nothing is charged until the trial ends. Change or cancel before then from Settings, Billing & products. If a payment doesn’t go through, everything keeps running for 7 more days, then the site pauses until the card is fixed. Nothing is deleted, and paying brings it straight back.
Questions
How do I change plans or cancel?
From Settings, Billing & products. Changes are prorated.
Why does it ask for a card before the trial?
So nothing stops when the trial ends. The card is saved, not charged, until the last day of the trial.