From Jomres v4 manual

Introduction

This article is a quick clarification of recent changes to Jomres and how it is licensed.

Previous to December 2009 Jomres was licensed under a proprietary license restricting the number of servers you could install Jomres on. As of the first of December 2009 all versions, both previous to that date and until further notice the PHP files in Jomres (unless otherwise licensed by their respective copyright owners) are now dual licensed under the GNU/GPL V2 and MIT license, choose whichever suits your circumstance best. Note, however all images, css and javascript which are copyright Vince Wooll/Woollyinwales IT are not GPL/MIT licensed and are not freely distributable.

No encoding, no restrictions, just great software.

If you're considering writing a Jomres plugin, be aware that I do not consider software that uses Jomres functions or classes to be derivative of Jomres. This means that you can license your plugins in any way that you wish.