Looks like if you get the PRO version, which is Mac and iOS, it is $129.99/yr or $14.99/month

I haven't used Logbook Pro so I can't really compare the two. When Logten Pro started charging annually, I was upset, but decided to pay. I still use it and think it is probably the best e-logbook out there. I would definitely recommend for Mac/iOS even having to pay a subscription