Had to downgrade from osx sierra. Sierra wreaked havoc on my mac. Lost the use of many applications mainly Logic Pro. Had to go back to the most stable osx which is Yosemite. Did a clean install. Quite easy. Now everything is back to normal. Logic Pro working fine plus all 3rd party applications working fine. Will not upgrade for the foreseeable future.
I purchased this key to reload a pro book but I am having difficulties at present.
The software I am sure is fine so it is possibly either the machine or me.
The wonder of computers!!