A licence like a Creative Commons cc-by-sa is not exclusive, and allows the copyright holder to do what they like with their work. What they <i>can&#x27;t</i> do is revoke the licence terms from anyone who chooses to exercise them. At best, the copyright holder can request removal of attribution.<p>In another comment I mention the Geograph project which uses cc-by-sa. For some more background to that, I wrote about the reasons for selecting that licence to ensure long-term freedom of the archive here: <a href="http:&#x2F;&#x2F;www.geograph.org.uk&#x2F;help&#x2F;freedom" rel="nofollow">http:&#x2F;&#x2F;www.geograph.org.uk&#x2F;help&#x2F;freedom</a>