High end update for client

Hello,
My client somehow got your theme when he purchased his hosting about a year ago with JustHost and now we want to update the theme to work with WordPress 4.6.1. I have tried to look for documentation regarding how in the world my client got the theme but we cannot find anything regarding purchasing this theme. What I think happened is when he purchased his hosting with JustHost, they offered to install the HighEnd theme but not maintain it.
Could we either get the files to update the site OR if we need to purchase again, how can we do that and keep his site the way it is: http://www.northupjets.com