That's correct. It's a one time fee for the app. If you buy LogTen Universal you get the iPhone and iPad versions for one price. LogTen for Mac is a separate program just for Mac OSX.
You can find LogTen Universal and LogTen for Mac Links to the iTunes store at
Airline Pilot Hiring - Pilot Store
For airline types interested in tracking FAA Part 117 Duty / Rest Limits you can easily do this in LogTen Pro with custom limit groups. There's a link that describes exactly how to set these up at
www.facebook.com/AirlinePilotHiring