Treat it like any other URL shortening: replace it by the original URL. It doesn't matter why the URL was obfuscated, the post must contain the intended target URL.
If the sole point of the post was to share an URL that pays the poster, then the post is spam. Otherwise ignore the revenue aspect.
If you notice that a user is using URL shortening (paying or not) on a regular basis, point them to the consensus that URL shortening should not be usedthe consensus that URL shortening should not be used (except when there's a very good reason, but you can leave this part out: “never obfuscate URLs” is a very good first approximation).