Note: yearly subscription is charged in a lump sum. We will charge the whole amount if you pick that option. You will not be able to request a partial refund on the days left if you decide to stop using the product.
Open the app on your Windows device. In the left menu at the bottom, you can find the "Upgrades" section. Open that section to choose and purchase a subscription plan. That is a recurring purchase; the subscription will renew at the end of a billing cycle.