I'm not a lawyer, maybe it wouldn't hold up in court, but I imagine that good will is the driving force, even if way down the line they may not manage to actually reclaim the money. My experience of working with cloud providers is that they are almost always happy to take a short term loss (extended trial, more test resources, refunds for accidental usage, etc) to get an account that is going to grow and stick with the provider. This does make sense, customer acquisition and churn are expensive, and recurring revenue is great.