...There's no way to protect a web game, by definition, since any browser has to load it all in order to play. And if a browser can do it, wget can do it, even if you try silly things like disabling right-click.
That said, if you're selling the sources, that's a downloadable file and another story entirely. People will have to pay before they're allowed to download it. But even then you have to rely on their honesty not to share with others.