WordPress 3.0 Multi-Site Enhancement: Now you can pre-populate your license key for multi-site installs. You can pre-define the license key in your wp-config.php file by adding define(‘GF_LICENSE_KEY’,'YOUR_KEY_GOES_HERE’);.
Well.. after loooong time, i return wordpress development. Firstly i tried to install gravityform @ multi-site but..
define(‘GF_LICENSE_KEY’,'YOUR_KEY_GOES_HERE’);
is not worked for me. I tried to add this code after i activated plugin. I tried re-install but still didnt worked.