What stops &quot;free content&quot; creators from suddenly making their content copyrighted, and suing everyone who has used their previously free material?
<p>For example, pexels.com has a lot of stock images, free for any use including commercial sales, without attribution.</p>
<p>The content creators, i.e., photographers, know that by uploading their photo to that site, they give it away for free. But what stops them from suddenly deciding to re-license their photo to no allow commercial use any more then deleting the photo from the free website? Then suing people who have used those photos commercially?</p>

<h2>It depends on the terms of the licence</h2>
<ol>
<li>You can do X until I tell you to stop</li>
<li>You can do X as long as Y</li>
<li>You can do X forever</li>
</ol>
<p>are all valid licences.</p>
<p>For the <a href="https://www.pexels.com/terms-of-service/" rel="noreferrer">website</a> you name, the licence is “worldwide, non-exclusive, <strong>permanently, irrevocable</strong>, royalty-free”.</p>

<p>&quot;License&quot; means permission. Once you've given someone permission to use a work, they have permission. Unless there were qualifications in the original permission, you can't take permission away by &quot;re-permissioninng&quot;.</p>

<blockquote>
<p>What stops “free content” creators from suddenly making their content copyrighted, and suing everyone who has used their previously free material?</p>
</blockquote>
<p>Simple: they can't &quot;suddenly make their content copyrighted&quot;. Content is automatically copyrighted as soon as it is created. (Assuming it meets the threshold of creativity required for copyright. If it doesn't, then it is simply not copyrighted at all.)</p>

<p>Every common free-content license has a clause specifying that it's irrevocable.  Sure, the content creator <em>could</em> sue, but an even-halfway-competent lawyer could point at that clause and get the suit dismissed, with an order for the content creator to pay the defendant's legal costs.</p>

copyright commerce