New template

Hello, I have my website www.lieshuyskens.com now hosted with Bluehost and I have the themes of "The theme foundry". Is it possible that I change my website to the following theme: https://catchthemes.com/demo/clean-fotografie/style-guide/gallery/? How does it work? I pay once for the pro version? Or do I have to pay for it annually? Kind regards, Lies Huyskens