The date that you purchased the scenery doens't mean anything. What's important, is the date you downloaded the installer.
If you downloaded the installer in May, the fact that you bought the scenery in June doesn't automatically update the scenery, because there's no "full" version download, the only installer we have is the Trial version that can be unlocked whenever you want so, if you have purchased using an old installer, the purchase is fine, but your scenery still needs to be updated, by downloading the latest version of the Trial.
Also, the fact that you purchased KLAS doesn't have anything to do with what you see on the Add/Remove programs list. This will show you everything that you have *installed*, regardless if you have purchased it or not. So, if you don't see anything related to KLAS, it can only mean you have forgot to install the Full installer, and installed only the Update, because the Update installed all by itself, will not appear in the Add/Remove programs so, you might see some scenery, but it's not complete.
If you already downloaded the upgrade, this should be enough, but you need to install the Full version first, it doesn't matter which one, as long as it is a full version, and you run the Updater after it.
Or, if you don't mind downloading a bigger files, just download the Full installer again, and get rid of everything else you have.