Is the free plan really free?
Yes. A free site has no expiry date and no card on file. It keeps working
indefinitely on its masthead.site address.
Do I pay per account or per site?
Per site. You can run several sites from one account and license only the
ones that need a custom domain or collaborators.
What happens if I cancel?
The site stays licensed until the period you already paid for runs out, then
returns to the free plan. Your content is untouched.
How do I change or cancel my plan?
From the site's Settings page, under License. That opens the billing portal
where you can switch plans, update your card, or cancel.