Turbo.264 HD is no longer developed - it has reached the end of its life.
It is a 32-bit app, so it will not work with any future version of macOS that is 64-bit only.
Apple has not yet announced which future version of macOS will be 64-bit only, but macOS 10.14 may have some significant changes as to how 32-bit apps are handled.
See this article for more information:
32-bit app compatibility with macOS High Sierra 10.13.4