For others wondering about how this works and considering their options: I've spent a significant time around lawyers who do license/copyright work for the two

For others wondering about how this works and considering their options: I've spent a significant time around lawyers who do license/copyright work for the two startups I've worked for. I am not a lawyer myself and this isn't legal advice. This is a fairly standard dual-license setup where the author hopes to offer the software for free to other open source creators and providers but wants to take a small rake from commercial entities that use the software. "Dual-license" refers to the fact that by default this code uses one license but for a fee, it can be used under a different license. Some libraries are dual-licensed but do not require a fee but instead allow consumers to choose which license they would prefer to use the code under. jQuery fell into this category for a long time[1]. The first and default license that this code carries is the AGPL. High-level notes about the AGPL: * Requires[2] code "linked" with this code in an application to be Open Source. * Requires changes to this code to also be free. * Is a derivative of the GPL designed to cover holes in the "linking" terminology that allowed networked software to skirt the "linked code must be free" requirement. * Plays nicely with other OS licenses such as the GPL, WTFPL, MIT, Apache, BSD etc. in that it doesn't require other code "linked" with it use the AGPL but does require them to be Open Source. The second license, which requires a fee, allows the code to be used under a different set of restrictions. In this case, the only restriction appears to be the number of uses of the code. This effectively frees a private entity to make modifications to the code and to "link" it to other code without having to share those modifications or the linked code. 1. https://blog.jquery.com/2012/09/10/jquery-licensing-changes/ 2. My understanding is that using AGPL code in a commercial application is usually advised against by corporate lawyers who work with IP/Copyright issues. To my knowledge, it's never been tested in court but no one is excited to be the first to try and therefore it's a risk rarely taken.