I am quite keen to try out drone.io but just wanted to know the differences between an open-source and enterprise edition. Unfortunately, there is no comparison table on the website.
The official pricing link says
We do not have a free option at this time. If cost is a concern, you have the option to download and install the open source edition of Drone on your own servers.
But looks like there are some hidden limitations. Few of them have been identified here.