On the second computer, SnagIT does not show as purchased but just shows the price. However, with Techsmith SnagIT, on the first computer, I installed it and it is still showing the purchase price instead of installed. I was then able to go on to my Apple Laptop and directly download it as iWorks was now associated with my Apple ID. When I installed iWork 09 on OSX, the Apple App Store noticed this installation and it allowed me to upgrade to the latest version. I have two scenarios, purchased iWork 09 with physical media installed on OSX Mavericks and purchased Techsmith Snagit (5 seat license) from Manufacturer's Online Store.
Being a new user to Apple, I'm trying to figure out a gap in the communication between the Apple App Store and software Installed.