Is it possible to upgrade a computer that qualifies for Mavericks to Mountain Lion via a content code purchase from the Mac App Store?

Question

I inherited a situation where a previous consultant purchased a Mountain Lion installer code from the Apple Store but Mountain Lion was never installed. I obtained a new installer code from Apple based on the valid purchase of the Mountain Lion software last month.
The Mountain Lion installer appears under Purchases in the Mac App Store, but nothing happens when I try to download it. When I try to redeem the purchase by inserting the content code I get a message indicating that the content code has already been redeemed.
I don't mind spending $20 to purchase a fresh content/installer code, but I would like some assurance that the Mountain Lion software can be installed on a computer that qualifies for Mavericks. Not wanting to upgrade to Mavericks is not my idea but is that of my client.
Or to put it another way, does Apple prohibit such an install unless the computer in question does not qualify for a Mavericks upgrade?

Answer 1

It is your decision which OS you want to upgrade to - Apple does not place such restrictions (unless the machine specs do not meet the OS's specs or vice versa). So, if yours does meet Mavericks specs, it can run any OS newer than what it came with.
So, which OS does the machine have now?
I inherited a situation where a previous consultant purchased a Mountain Lion installer code from the Apple Store but Mountain Lion was never installed. I obtained a new installer code from Apple based on the valid purchase of the Mountain Lion software last month.
Was this purchase done on this same Mac? If so and someone else purchased the OS, then the likely answer is: any OS or app obtained at the app store is not transferable - its' license is tied to the original purchaser's Apple ID forever. So, it may have been a valid purchase, but it is tied to the purchaser, not you.
In order to get past that, you will need to wipe the drive booting from either the original install disk (which OS did the Mac come with?) or using recovery if it was Lion. After wiping the drive, reinstall the original system, and then you can purchase and download any OS version you'd like using your own Apple ID.
Let me know if I misunderstood the situation.