I remember WhatsApp costing money, 1$ per year or per lifetime or something. I paid for it, I think it was a WinRar situation though, where deleting and reinstalling the app gave it to you for free or something.
I'm guessing most people didn't pay though, since they scraped the fee (even before FB bought them). I guess it was just too little money to be worth the effort.
Other way round. Facebook bought them in 2014, and they dropped the fee in early 2016.
The fee wasn't enforced in many developing countries, and some users elsewhere will have been jumping through the delete-and-reinstall hoops (which was painful because it lost chat history) to avoid paying.
But with 1bn active users at the time the fee was dropped, it would still have been bringing in more than enough revenue to have sustained Whatsapp as an independent business if they had chosen not to sell to FB.
Pre acquisition Whatsapp had 450M users. Even accounting for half the revenue of 1$ going away for payment fees (30%) and taxes (20%), that would still have been a nice cushy 200 million $ a year in almost pure profit - WA had 55 (!) employees at acquisition and 550 servers [1].
That's nothing at this scale of users and speaks volumes for the ingenuity of their staff.
The only ones driving even leaner than that are StackOverflow with just nine servers [2].
That fee wasn't really enforced. I was in India at the time and no one paid because no one had credit cards tied to their account. Everyone still used WhatsApp just fine.
I'm guessing most people didn't pay though, since they scraped the fee (even before FB bought them). I guess it was just too little money to be worth the effort.