If you are running a machine that has been disconnected from the internet for security reasons, or if the specific Adobe activation servers for CS3/CS4 have been retired, the software cannot complete the handshake. In some cases, the failure to connect to the server causes the software to default to a "Trial" or "Unregistered" state, prompting for the serial number.
: Sign in to Adobe Accounts to view registered products and retrieve serial numbers. Adobe Illustrator Asking For Serial Number Mac Os X 10.6
If you have tried all fixes (including phone activation and date trick) and Illustrator still demands a serial number on Mac OS X 10.6, recognize that Adobe’s legacy infrastructure is largely gone. Your remaining options: If you are running a machine that has
Before troubleshooting, ensure you are installing a compatible version: If you have tried all fixes (including phone
Because Adobe’s online activation servers for Snow Leopard-era apps are mostly dead, phone activation is your last resort.