The program is telling you that O'Hare is installed but not activated, not because the scenery is there, but because you have inserted a serial number for it, which is not activated, probably because it's a fake one so, you will keep getting that question forever, unless you clean up the wrong serial number for O'Hare, which can be done by removing the HKCU\Software\fsdreamteam\OHare key from the registry.
Also, you don't see KLAS in the menu, because you are probably trying to use KLAS with an old (fake ?) Addon Manager version, that will obviously never work with it. So, in order to have KLAS and all other recent sceneries working, you need to use the current version of the Addon Manager (that comes with KLAS), they will never work with older versions.