====== I am asked again and again to enter the serial number - why? =======

The Settlers 3 serial number must be entered once in Settlers 3 itself. If you receive the above message again and again, proceed as follows:

  - Start The Settlers 3 without using aLobby by directly running the s3_alobby.exe file.
    * Tip: For the file to exist in the Settlers 3 folder, the aLobby must already have been installed and started at least once.
    * Default directory Gold Edition: C:\BlueByte\Siedler3
    * Default directory Ultimate Collection: C:\GOG Games\Settlers 3 Ultimate
  - Start a multiplayer game in Settlers 3. This way you will be asked for the serial number.
  - Enter the serial number, click Ok.
  - Exit Settlers 3.