I have been asked to provide the license details of all the software libraries used in a software. It should have been an easy task since the customer provided the full sources for them.
Unfortunately, among others I've noticed that Highcharts sources (version 2.1.4) do not contain any license.
All I can find is:
* @license Highcharts JS v2.1.4 (2011-03-02)
* (c) 2009-2010 Torstein Hønsi
* License: www.highcharts.com/license
Now, I will contact the company to know what the license was back then.
But that made me wonder: can such unstated, untraceable and mutable contract be enforced in a court?
I mean, whatever license Highcharts had back then, the resource pointed by the url may have been changed by the company, hacked by an attacker and so on...
There is no way (that I can think of) to prove that the license was a particular one, just like there is no way to prove that the a page referenced by a particular URL had the same content it currently have.
Obviously, Highcharts still reserves the copyright so that probably it does not change much from a legal perspective, but this might impact other open source project depending on Highcharts (as the software in question) that could not prove all their dependencies are actually good for a specific application.