The key is public by nature — it travels in the page source. It only works on udata.stream: a request from anywhere else is served, but never counted.
pk_d3d03086d89647ae26921b94
<script src="https://relay.mib.news/w.js" data-key="pk_d3d03086d89647ae26921b94" data-count="4" async></script>