In the computer world if you say something is unbreakable you're just making yourself a target. DRM's don't work, they can just frustrate your customers and make them stop buying your products. There will always be somebody more determined to break into your game then you were in protecting it.
Leasing Spore from EA is not what customers want. Now people who didn't even pay for it have unlimited access to it. Think about that quote from Star Wars, the more EA tightens it's grip, the more customers will slip through their fingers; and good riddance too, they've brought down so many games by limiting development time and money and publishing games that weren't even finished until a year after their release.