I'm interested in using the JSXGraph JavaScript library in a website project.  The library is covered by the LGPL and MIT licenses.  I'm new to licensing and am trying to answer the following question:Suppose I build a subscription-based website that allows users to buy monthly access to the site.  Users would be served proprietary content and be able to interact with dynamic widgets built on JSXGraph.  What responsibilities do I have to customers or the license holders themselves?Does the answer change if instead of a website, I build a mobile app that serves the content and dynamic widgets?
Implication of LGPL and MIT licenses for commercial use (of JSXGraph library)
lgpl
While the project website is not that clear, the README on GitHub is much clearer:JSXGraph is free software dual licensed under the GNU LGPL or MIT License.Dual licensed means that you can choose which license applies to you. For commercial use, you will be better off choosing to follow the MIT requirements only: it is less complicated to comply with MIT than with LGPL.The only condition of the MIT license is:The above copyright notice and this permission notice shall be included in  all copies or substantial portions of the Software.That means that your app (whether web app or mobile app) should contain an About page (or a Licenses page, or something like that) where you reproduce this notice, preferably with a link to the project page as well (but that is not part of the requirement).