It's worth it, otherwise I wouldn't have installed it! I don't get any of the money from that, it all goes to the developer. However, after trying the app on my photography forum for a couple months, I determined it was stable and works well.
By the way, this APP will work with more than just railroadforums. For starters, it works with modelrailroadforums. It also works with PNWphotos.com and lots of other forums as well. You only pay once, there is no fee for using it on another forum.