A lot of the comments on here are pointing out that OnLive is a subscription service. This is not the only pricing plan they have available. Looking at their documentation on "Getting Games in the OnLive Game Service" you will notice their are multiple avenues to purchase a game.
The subscription service they offer is for a collection of ~80 titles. For most newer titles you purchase a pass to play the game. This allows access to the game for a timed interval (think multiple days like renting) or unlimited play. That is a one-time purchase just like if you purchased the title off of Steam or in a retail store. Does the full pass require a subscription? Nope. Please take a look at the documentation and pricing model before making your claims.