To add extra features find the Subscription and billing sidebar on the left-hand side of the admin portal, there you will find just below the add extra features button. Once you have clicked on the Add extra features page you will see the vast collection of features Paytia consist of. (The features available will vary on the package you have purchased)
The features you have already purchased will be highlighted green titled License already purchased and the features that have been previously purchased will be placed at the top of the page. From here all you need to do is press on Buy now to purchase any of the features that you desire.