Plugin licensing
From Sohowiki
Quick Overview
The license check doesn't happen unless you've submitted your plugin to the addons website. So until you do that you don't have to worry about it.
Then, even after you have submitted your plugin to the Addons website you can still test it on your own sites by using test licenses. You can manage your test licenses by logging-in to the Addons website, going to "My Addons", then looking under "Developer Tools" and clicking "Manage Test Licenses".