[thrownaway2424]

That's not a very useful service if the memcache can disappear. It's difficult to properly provision a service when the average case costs X and the worst case costs 1000X because the cache layer is "ephemeral". When the cache is working your cost utilization will look like shit and your financial management is going to ask you to cut costs. Then you'll do that and when the cache suddenly disappears, you'll suffer an outage because you are out of capacity.

So I think it's not very reasonable to offer no-SLA components of a hosted platform. It's either there with some assurances, or it might as well not exist at all.