in-app purchases? – Symbol Keyboard - 2000+ Signs Review

In summary, good app for copy and paste symbols which are not available in default iphone keyboard. However, every time i open the app, i would be viewing ads which is a bit annoying. I notice in your in-app purchase list that can either remove ads and unlock all features. The question is how i am able to pay for these features but there are no specific buttons in the app that would redirect me to do purchase the in-app features?
Review by scribe who scribes on Symbol Keyboard - 2000+ Signs.