[flashmob]

> They register again and again after the trial has expired

This is great! You have users who are using your product, how could you not be happy? Find out why they are not converting, perhaps your offer isn't that great for their demographic? Note that even if they didn't pay to your service, they may be your biggest fans who may recommend your product to other people. DEA users are usually tech-savvy types, they are also the kind of people who are the early adopters when it comes to tech (since they were able to figure out how a DEA works & how to use one), and are probably the ones who normal people go to get advice. Don't forget that even if not a paying customer, they are still a customer in the sense that they could review your service or refer others through word of mouth! If you're blocking DEA services, it may end up costing you more.

[nirvdrum]

That's a whole lot of "what ifs". I'd rather just block people that are consuming resources and potentially affecting service levels for actual customers (or people that will actually convert). The situation you paint might be true of a very small percentage. But more often than not it's just people that want to use something without paying for it.

[chii]

> want to use something without paying for it.

So don't let people use your services without paying! A trial is only a trial if it locks or stops the user from using it after a trial period. Freemium models that limits number of uses aren't a trial.

[fjsolwmv]

Why not make the whole business model "pay what you want"?