You buy the game with a single payment and own it on your account permanently, unless it is refunded or otherwise revoked (payment fraud, etc.) The plus side of digital distributions is they don't take tons of room, are easier to search and receive updates (e.g. new OS and hardware optimization, bug …

Update: I take it back! It's NOT the Layout.dll at all! You know how one can drag another icon/shortcut *above* the Programs item on the Start menu? If I remove that icon (in this case the default 'Windows Update' shortcut icon), then the 'Windows ME Millennium Edition' text would disappear, and …

The banner should be stored as a bitmap in Explorer.exe, did Explorer.exe get modified (likely unintentionally)? Can you open it with Resource Hacker or something to see if the banner is still there?