Why iWork in Mac costs and in iPad or iPhone is free?

Keynote for Mac is free for owners of a Mac if it is installed within 12 months from date of purchase.

Keynote for iPad or iPhone is free for owners of a mobile device if it is installed within 12 months from date of purchase.

Purchasing an iPhone or iPad does not qualify for a free install of Keynote on a Mac.

Purchasing a Mac does not qualify for a free installing Keynote on mobile devices.

It is one of the first downloads when you do a update in the app store when you buy a mac

Keynote is available for purchase to anyone with an Apple ID and have the Mac App Store installed on their Mac, it can only be downloaded if it has been purchased.

A free purchase of Keynote is only available to users who qualify: Keynote for Mac is free to owners of a Mac if it is installed within 12 months from date of purchase of a new Mac