evidence: Facebook has acknowledged that it considered charging for access to user data. But Facebook has challenged the significance of those discussions, telling the Wall Street Journal last year and NBC News this month that the company was merely mulling various business models. [...] Facebook executives, including Zuckerberg and Sandberg, spent months brainstorming ways to turn the company around. An idea that they kept returning to: make money from the app partners, by charging them for access to Facebook’s users and their data. [...] Even though Facebook eventually decided not to charge developers directly for access to user data, the extensive discussions around its monetary value, shown in the leaked documents, could create lasting problems for the company, privacy and policy experts say.