From The First Law Of Internet Physics by Fred Wilson:

many users * low arpu >>>> few users * high arpu

I’ve seen so many people try paid content on the Internet and the result is less users, a lot less. You can extract a higher average revenue per user (arpu) from a paid model, but you get so many less users that is it better to extract a lower arpu with a free model and get many more users. I guess a corollary to the first law of Internet physics is that you can implement a freemium model on top of a free model and turn some of your users into high arpu customers, but they will always be a small portion of the total number of users.

That’s a long way of saying that you can do paid, but you had better have a free tier first and foremost as most users will go for that. And if you put too much of your content behind a paywall, you’ve effectively turned your core product into a paid one and you are back to {few users*high arpu}. So be careful with the freemium offering.