@RadioMan71 Your saves are stored in the folder titled Saves; each save has its own folder with a handful of files inside. Your store content is bundled into .ebc files, and your custom content into .dbc files, both in DCCache. For premium store content to work, you also need your ccmerged.package file from DCBackup.
But again, the best way to troubleshoot is to pull the entire TS3 folder and all its contents—everything you see in that screenshot—out of Documents at once. Don't just move one of the folders inside, remove the entire thing. Then launch the game again, quit, install a store item, and load a new save to see if that item appears in-game. If one of your .ebc files is corrupt, or your ccmerged.package, that would explain how some of your store content keeps disappearing. If that's the case, you'd have to rebuild a significant portion of your store content anyway, so you might as well experiment with a clean folder.
I did want to clarify: When you play while offline, you won't see the items from the in-game shopping experience. This is not the same as having your store content removed from your game folder. I always play with this shopping feature turned off; it's not necessary to buy store content or to make it work.
