If I buy the Pro version, will it work on my other devices?

If you purchase the Pro upgrade it is linked to your iTunes Apple account. This means it will work where ever you use that account. Note however, that the Mac and iPhone/iPad applications are separate products and require separate upgrades.

If you upgrade on one iOS device, say your iPhone, then you can unlock pro on your other iOS devices (e.g. iPad) by tapping ‘Restore Previous Purchase’ in the Upgrade screen.