I purchased notability on my ipad and I would like to put it on my MacBook Pro as well, however, while I try to download it from the Mac Store it prompts me to pay $9.99. How can I keep from paying twice for the same app?

Mea culpa; mea culpa. Mea maxima culpa.

Even though I thought I'd thoroughly read the Notability listing on the iOS App Store and reviewed the Ginger Labs website, I was wrong. I wrote to Ginger Labs (through their support page) and received a speedy reply from "Carlton."

There is a note on Ginger Labs' support page. The first link under "General Information" is "Buying Notability for iPad, iPhone, and Mac," and that article clearly says: "To use Notability on iPad, iPhone, and Mac, it will need to be purchased twice: once in the iOS App Store and once in the Mac App Store."

Moreover, the iOS App Store description does include the note "Mac app sold separately" at the bottom of the (long) description.

It is one thing to have missed these before I purchased the app, but it's another thing entirely to have missed them when I was looking for them before I posted to this discussion thread.

So: Sorry, Ginger Labs, and thanks to Carlton for his speedy & courteous reply.

I, too, was puzzled by this circumstance and very disappointed to discover this thread on an Apple discussion board more than three years after jjmccormick08's original post. It never occurred to me that I should research the veracity &/or reliability of the descriptions of the applications made available on Apple's stores.

"Misleading" is the kindest word that can be used to describe Ginger Labs' own website and its listings on Apple's App Stores. The Ginger Labs site proudly proclaims, directly over a graphic showing an iPad, iPhone and a MacBook Air: "All you notes, one place. Stay organized and up-to-date wherever you are. At home, in the office, or on the road, your notes are always with you, thanks to iCloud." Nothing in any of the Ginger Labs' Notability listings explicitly says that two instances of the app -- one for iOS and one for MacOS -- must be purchased to make this happen. The only suggestions are (a) the compatibility declaration (a different one on each page) and (b) a link to the other app store page for the other version.

Apple customers have every reason to be disappointed & annoyed by Ginger Labs' (apparently intentional & clearly ambiguous) omission. Like Notability, Apple's Pages, Numbers & Keynote apps share content across iOS & MacOS platforms via the iCloud; similarly, Evernote's free version also has apps for both iOS and MacOS, as do many, many other apps. The problem could be simply solved with a little note in the App Store listings and on Ginger Labs' own website that says (something like), "Cross-platform functionality requires purchase of both Notability for iOS and for MacOS." Both Apple & Ginger Labs should be embarrassed by this.

At this point, I've just started using Notability on my iOS devices; I don't know if I'll have need of it on my MacBook, but this leaves a very bad taste. As a matter of principle, I'd return the app for a refund and buy something else, if I could.

This is not the same thing actually. Windows and Mac have vastly different ecosystems, whereas Apple's ecosystem is pretty consistent between Mac and iOS. So for Ginger Labs to charge you $10 to use one app with similar features two separate times is immensely silly. I currently share notes with myself as PDFs in order to use notes I've made on my iPad on my MacBook, which undercuts the reason I switched to Apple products in the first place - an interconnected ecosystem. So bad on you for charging $20 for a note-taking app, Ginger Labs.

You have to pay for it. It's a different app.

It's not the same app. One is written for iOS and the other for OS X (Mac). Just like most applications would make you buy both the Windows and Mac version.