You should have gotten a single serial # and 2 key codes with your new package. One for the runtime and another for the clients. The same serial # is used for both. All you have to do is go to Options >> System >> Change Client License >> Add. Then just type in your organization, serial # and keycode for your clients. The fact that you have the development license should not make a difference. You can inter-mix different serial #s between registration info and client info.