On the Pricing page, choose the plan you want and click Get [plan]. You'll be taken to a secure Stripe checkout to enter your card — once it's done, you're on the new plan right away.
Manage your subscription Go to Account → Billing and click Manage subscription. This opens the secure Stripe portal, where you can update your card, change your plan, or cancel.
Invoices All your invoices are listed in the Billing tab — view or download each as a PDF.
Cancel anytime Cancel from the Stripe portal whenever you like. You keep your plan until the end of the current billing period, after which your account reverts to the Free plan.