Our plan is to keep an open host version. We will also continue to improve the plugin structure, so that also closed source, any one can add his functionalities. So the difference is not as big as one might think.

@kscharf You can surely use the free host version for free. We make our money with customized version for printer vendors, who pay a fee to get a optimized version for their printers with included drivers, printer settings and slicer settings.
(bold italics mine)

http://forums.reprap.org/read.php?26...627#msg-333627