https://phys.org/news/2018-12-uk-parliament-internal-facebook-documents.html

"There's a big question on where we get the revenue from," CEO Mark Zuckerberg said in one email. "Do we make it easy for devs to use our payments/ad network but not require them? Do we require them? Do we just charge a rev share directly and let devs who use them get a credit against what they owe us? It's not at all clear to me here that we have a model that will actually make us the revenue we want at scale."

The parliament's Digital, Culture, Media and Sport Committee received the documents from app developer Six4Three, which had acquired the files dating from 2013-2014, as part of a U.S. lawsuit against the social media giant. The app developer is suing Facebook over a change to the social network's privacy policies in 2015 that led Six4Three to shut down its app, Pikinis, which let users find photos of their friends in bathing suits by searching their friends list.