Old addon problems

Quite a while ago I purchaced two addons for my FSX (Steam)
Addit Pro and Traffic 360
One of the problems with Traffic 360 is the Airport tower. The display is showing 'Trial period expired'. This only happens with the Tower display. I have entered the correct code.
To explain fully, I have started using FSX again after a few years away from it, but these old addons are giving me problems.
Some of my files have dissapeared from the scenery library after using  Addit Pro. In the Scenery Library, (Settings) some of the scenery area are blank, but they are ticked and showing the priority number correctly. One of these blank spaces should be 'Addon Scenery' which is usually priority 1.
I tried uninstalling FSX, deleating all the computer files on my computer (That I could find) and re-installed FSX via Steam.
However the problems remain.
How can I reload a factory fresh copy of FSX from Steam, which will get rid of the above problems.
Cheers