: Adobe officially stopped supporting Flash Player on December 31, 2020. Major browsers and operating systems have since blocked Flash content for security reasons, making the output from Flash Professional CS4 largely obsolete for modern web use. Where to Find an Existing Serial Number
: Even with a 100% legitimate, original serial number, you can no longer activate Flash CS4 online. The aged-out servers were shut down, meaning the software cannot "call home" to verify the license. Adobe Flash Professional Cs4 Serial Number
If you are trying to retrieve a previously purchased serial number for your records: Flash Professional CS4 - Adobe Community : Adobe officially stopped supporting Flash Player on