It was this popular in 2012 already. For Android users first year was free and then you could be charged €0.89/year. I knew paying customers and was willing to do the same. It's a great product at a great price without ads, just take my money. I'd rather pay for a service than be monetized in exchange for using it.

BTW, they had just 50 engineers when FB bought them with 450M users (+1M/day) and they supported more devices back then. Just with those costs and the network effect, keeping the subscription model would have meant a solid source of honest revenue.