That's generally not what most people would consider a freemium/free-to-play title though - I'd just call that a demo. Freemium games generally have a time based element or other similar resource that replenishes slowly, and can be circumvented or accelerated by paying money.
I'm not sure that's true, I just think that's the most prevalent/profitable type of freemium game–one based on accelerating constraints.
Give your service away for free, possibly ad supported but maybe not, acquire a lot of customers very efficiently through word of mouth, referral networks, organic search marketing, etc, then offer premium priced value added services or an enhanced version of your service to your customer base.
