When publishing your Unity project to Flash, you will need to acquire a license from Adobe in order for the content to work in the Flash Player. The Adobe documentation of premium features explains why a license is required for Unity built Flash games:
"Premium Features includes the XC APIs (domain memory APIs in combination with Stage3D hardware acceleration APIs), which allows C/C++ developers and other developers using 3rd party tools, including Unity, to target Flash Player for the distribution of their games."
For more information and the latest details on the license, please refer to the Adobe article which explains this in detail.
To obtain a license, you will need to sign into https://www.adobefpl.com/ using your AdobeId and follow their instructions.
Page last updated: 2012-11-06