To change your WooRank subscription, to either upgrade or downgrade, click the “Change your plan” button on your account page:
This will take you to the Upgrade/Downgrade page. On this page you can select either a Pro or Premium plan or contact us to discuss our Enterprise solutions.
On this page you can also choose to upgrade from a monthly account to a year account. Just click the "Billed yearly" tab above the subscriptions options and choose the plan you want.