Do I need to buy touchable again?

Hi, I purchased touchable pro to use with my MAC and my PC (Windows). Now I want to use the MAC with iPAD (Latest model). I’ve tried to download the App to my iPAD (iOS) using the ‘App Store’ but it said that i need to pay for it. Should I need to buy the App for the IOS even i bought it already for MAC and Windows? thank you.