If you would like to switch from being billed monthly to being billed yearly or vice versa you can do so via the
Settings > Plan & Billing area of the Timeular app
You'll see a Billing period toggle on this screen which will indicate you're currently on a monthly billing plan:
Just click this toggle switch so that it displays the billing frequency you would like to switch to and then click on the "Confirm switch to yearly" button to make the change.
And that's it, you've changed your billing frequency. You'll receive an email with the receipt and invoice for the transaction shortly after you've made the switch.