I was able to reinstall v1.5 and I then registered it with my original key and it accepted it and I thought everything was all set.
Are you sure it was "accepted" ?
The Serial Number is accepted ONLY if, after you entered it, a dialog will say "Do you want to activate fsdreamteam GSX on this PC ?", you will need to reply Yes, another dialog will ask if you are sure, you'll need to reply Yes to the second dialog and then, after a couple of seconds, a third dialog will say the product has been activated successfully.
If you haven't seen this, simply inserted the Serial Number with FSX going back to fly without doing anything, it means the key hasn't been accepted, rather the opposite: you either entered something entirely wrong in place of the Serial Number (like the Order Number), or you entered your Serial Number correctly, but with another product selected.
When I tried to access it in FSX, however, it presented me with only 3 airports and stated that I was using the "trial" version
This confirms it's working correctly, and it simply lacking the activation. Note that, you'll will likely have to restart FSX, if you reactivated in the same session.
I copied and pasted the key I received in my Email conformation at the time of purchase and the screen then validated it and allowed finish of install.
So you see all the dialogs ? If yes, the Addon Manager should say GSX is now Active. This means it's Active
As I've said, you'll have to restart FSX to use it fully.
Is there a data file somewhere that might not have been updated? I can't use it until I get a resolution back. Hopefully you can help me with this today.
The activation works and will work if you did what I've said above, you might simply need to restart FSX. Check the Addon Manager, if it says "Active" for a product, then it's active.