It appears that I can purchase the developer license and install it on client websites. I understand that I will have to provide them support for the plugin, as they will not be able to come to you for support.
Assuming that all of the above is correct, how do you define "client?" Are clients anyone who purchases website services of any kind from me? Do I have to maintain a relationship with them beyond a one-time payment? Can a client be someone who purchases an entire website from me that has Gravity Forms plugin installed?