Build a Website for a software app

I am looking for a fully functional website for a new app with the following requirements: -fully functional and professional design -similar to the look of [login to view URL] -must supply all graphics and imagery (except for the screenshots of the app) -must be responsive and display well on desktop, IOS and Android -must be SEO optimized -will include a minimum of 5 pages including: -home page -download page -Buy now -FAQ/ Support -Contact page Buy now page must integrate a shopping cart that accepts payments and automatically issues license keys (such as [login to view URL])