Your name at the bottom of the sidebar → Subscription. The card at the top shows your current plan, its price, whether it auto-renews, when it next renews and which card it charges.
Two actions sit underneath: Change plan and Cancel subscription.
Changing plan
Change plan opens the comparison, with your current plan marked Active. Pick another and follow the checkout.
Free to swipesign Business is the move most people make: two users become unlimited, 5 AES a month become 100, and you get 5 QES every month instead of five to get started. You don't have to move because you've run out, allowances are soft limits and extras are billed per signature, but an extra AES is €1.40 on Free and €0.90 on the subscription (net, excl. VAT), so once you're paying for extras every month, do the sum.
Monthly or annual is the other switch. Same €49 a month either way, or €588 for the year (net, excl. VAT). The annual plan pools your allowances across the whole year and fixes the price for the contract year. See Compare plans.
Cancelling
Cancelling is free and takes effect at the end of the period you have already paid for, not immediately. Everything keeps working until then.
The monthly subscription runs month to month, so there is nothing to serve out beyond the current month. The annual plan runs to the end of its contract year.
The Free plan has nothing to cancel. It's free for as long as you like: no card, no expiry.
Download any invoices your accountant will want while you still have access. See VAT ID and invoices.