I have written a plugin. It will be called something like
ElephantPM Gantt Chart Lite
I will put this into the official WordPress Plugin directory.
I also want to make a chargeable version of this
ElephantPM Gantt Chart Pro
I would like to be like wpmudev and
* protect revenue with an API key
* provide automatic updates to "pro" customers.
What are my options? Which do you recommend?