To cancel your subscription, click on your name (bottom left), select "Subscription" to open the pop-up, then click "manage." This takes you to Stripe where you can manage your subscription.
You'll continue having access to paid features until your current billing cycle ends.
What happens to your credits:
Your remaining credits stay valid for 3 months from your last purchase date or billing cycle start. After this 3-month period, any unused credits will expire permanently.