Adobe officially shut down the activation servers for Creative Suite 5 (CS5) and Creative Suite 6 (CS6) several years ago. Even if you possess a 100% legitimate, historically valid serial number, the software cannot connect to Adobe's servers to verify it.
Any serial number widely available on the internet has either been blocked by Adobe’s activation servers or will stop working after a few days. Adobe has sophisticated license validation—even for older versions. Adobe Illustrator Serial Number Cs5 List
However, John soon realized that using a shared serial number was not the most ideal solution. He began to explore other options, such as purchasing a legitimate copy of Adobe Illustrator CS5 or upgrading to the latest version of Adobe Creative Cloud. Adobe officially shut down the activation servers for
He spent three hours in the digital underworld. He navigated forums that looked like they hadn't been updated since the Sparkle-text era and clicked through "Serial Number List" blogs that triggered every antivirus warning he had. He spent three hours in the digital underworld
Finding a lost Adobe Illustrator CS5 serial number is possible through several official methods, though Adobe no longer provides lists of serial numbers publicly. CS5 is a legacy product that reached its "end of life" in 2019. Official Recovery Methods Adobe Account Portal