If I purchase the iPad version can I access on my iPhone / Mac / Windows for free (and vice versa)?

If you’d like to run the app on multiple platforms, separate purchases are necessary. The reason for this is that each app runs on a completely different software platform. Because of this, apps for each platform have to be developed from the ground up and sold separately through their respective stores.
 
However, if you have purchased a productivity version, you can avail of a 50% discount off the original price of other productivity versions, or a $15 discount off the companion iPhone version.
 
Courses are available across all platforms with one purchase, and do not require separate purchasing on each platform.