It never ceases to amaze me how many people "fall" for this "lifetime" pricing model. In fact I said the exact same thing three months ago [1].
The fact that the service provider is not getting any future revenue from you, even if they've fairly discounted your lifetime value, gives them the incentive to get rid of you.
Additionally it gives the wrong incentives to users to "abuse" their "unlimited" service. You saw this with AT&T's "unlimited" wireless data plans recently [2].
I know why people do it: as an alternative to raising capital. Businesses do Groupons for the same reason. In fact, I'm feeling like a broken record here [3].
The problem with Groupon (and similar "offer" sites) is they create the wrong incentives and attract the worst kind of customer. The best situation for Groupon and for businesses is for lots of people to buy the offers and then not to use them.
The lesson here is that if you want to create a sustainable and liked business, you need to align your incentives with those of your customers [4].
As a customer, stop falling for this charade.
As a business, stop taking short term cash flows for perpetual liabilities just to raise capital.
Seriously.
EDIT: regarding "unlimited" (in Karunamon's comment), he is correct: we do need to hold companies to a higher standard. For example, Australia's ACCC (I guess equivalent to the FTC but with a heavy focus on consumer rights) has cracked down on the use of "unlimited" (eg [5]).
But that just reinforces my point. In Australia pretty much all Internet plans have stated quotas. With unlimited plans you create the wrong incentives to throttle users, impose nebulous "fair use" conditions and generally whittle away at what's really "unlimited".
It's the wrong incentive system.
With Internet quotas at least you know you're getting what you pay for and your plan is priced for your usage, not some median or 95% usage that will constantly have the provider trying to throttle "power users".
[1]: http://news.ycombinator.com/item?id=3936701
[2]: http://mashable.com/2012/03/01/att-limits-unlimited-data/
[3]: http://news.ycombinator.com/item?id=2649739
[4]: http://www.accountingweb.com/blogs/ronaldbaker/firms-future/...
[5]: http://www.lifehacker.com.au/2010/12/accc-taking-tpg-to-cour...