Lee, Clarence, Vineet Kumar, and Sunil Gupta. "Designing Freemium: A Model of Consumer Usage, Upgrade, and Referral Dynamics." Diss., Harvard Business School, 2013 ...

Magazines are one more category that is taking advantage of the freemium pricing model. GigaOM didn’t envision this exactly back in February when Apple let in-app subscriptions into the stores.