Adobe Illustrator CS3 is now considered "legacy" software, originally released in 2007. While it remains a nostalgia-heavy favorite for its lightweight performance on older hardware, the way users manage its licensing has changed significantly over the last decade. 1. The Death of Activation Servers
If you need Illustrator but want to avoid a subscription, consider these options mentioned in the Adobe Community: Adobe Illustrator Cs3 Serial Number UPD