It means to involve a trusted third party in a transaction to oversee the payments and timely execution of contractual terms by the parties involved. (bestsampleresume.com)
A legal background, which is useful to apply legal construction to contractual terms in a manner that would be similar to a court. (slaw.ca)
Then, after a book had «earned out», the author would receive a royalty based on contractual terms. (madgeniusclub.com)