To upgrade from one plan to the other all you have to do is go to your dashboard and select My Apps. In this section, select the app that you want to upgrade, and then click on Upgrade Plan. Here, you would be able to see the current status and plan of your app. Also, you would be offered various options that you can subscribe to, and you can choose from Monthly or Yearly subscriptions of Platinum plan, Gold plan or Basic plan. After choosing the preferred subscription you can even choose app add-ons as per your requirements. Once you have selected everything click on continue and then pay for your subscription and your plan would be upgraded.