No easy way, but is it that great a site that people would recreate email accounts over and over again to avoid paying? There are disposable email tools but you can have a go at blocking those domains.The usual way is to restrict some functionality until they pay for the service.
Nature of the app is you enter information about securities and the app watches them for you based on criteria you enter and it lets you know when to get out.
hey ethic if you and i were both courting lily allen..... oh wait, which one of us has a relationship that lasted more than the bus ride home?
If you require a CC you can check previous accounts for that card and flag it. Sure they may have different cards...
Presumably someone who wants to use the app for more than 2 weeks is going to want to watch the same securities on subsequent registrations. Your registration script could watch for similar patterns and flag new accounts that mimic expired ones, notifying the administrator to manually review. edit: On a side note, I know you're just building to the specs of your client but there are better and probably cheaper sites that do this, for instance http://www.zignals.com. Plus I'm pretty sure its a built in feature of most online trading websites too.
If someone wants to go through the trouble of making all those accounts....it sounds like you're reasonably enough prived for your service and client that people won't want to go through that hassle....
One to think about is: Why are the willing to through the hassle of opening multiple accounts, redoing the data, etc but aren't willing to pay? Is the price point too high? Is the service good but not good enough? Answer that and I think your time will be better spent.
ober, did your client actually ask you to put in a big ol' defense against the dark art of signing up for the free trial over and over? Sounds like it's a problem that doesn't really need to be solved unless they are specifically asking for it. I'd say that the money spent combating the possibility could end up being far more than the money that would be lost if you just let it happen.