I have put a lot of work into the Icelandic library and I always try to make sure nothing that’s copyrighted is being shared there without permission.
I have gone to great trouble to obtain permissions for a lot of copyrighted material and then put it into LingQ. I write how and from whom I got permission in the course description usually. I think what would be a great addition is that in addition to a “description” field, we could have “copyright” field for courses and/or lessons, where we could write why we are allowed to share the courses/lessons.