The key is public by nature — it travels in the page source. It only works on prismazilei.mib.news: a request from anywhere else is served, but never counted.
pk_87e16bb38a5074d8299dc823
<script src="https://relay.mib.news/w.js" data-key="pk_87e16bb38a5074d8299dc823" data-count="4" async></script>