FlexBuilder on Linux was an alpha product which was not licensed under Adobe Flex 3 license.
Also FlexBuilder on Linux is now a discontinued product and please find more details in this link
However one can continue using Flex SDK on Linux from command line.
Thank you for the response, but we really need the Adobe Flex IDE. We are happy with the alpha version we currently use.
Can Adobe send a fix to unlock this version for us?
Is there an alternative IDE we can use in Linux?
I forgot to mention that we purchased licenses for Windows in August 2009 because the Linux version was not released yet, but we have been developing with the alpha version for Linux since we purchased the licenses.