I have created a desktop application(winfoms) using C#.net 3.5, the application is an SEO application, so it has to be connected to the internet, i implemented a simple licensing routine where every time the application is started it will query the web service on my server with the key and machine hash to validate.But recently i have noticed that some crackers have disabled the license verification (simply removed the lines of code that does that) of the application which i have obfuscated, and the sad thing is that they are selling it at a cost that is only 10% of what i am selling for, they didn't even bother to remove my website address and company details from the about box. The application is having an auto-update feature, which they so-called crackers have intentionally left it on in the cracked versionI was just trying to figure out a way out of this, i can release an update and disable all the versions that are brought from the crackers, but without a proper licensing it will broken again and the next time, i don't have the guarantee that they will keep the auto update feature on.
Licensing for a web based desktop application?
.net;winforms;licensing
In your next update, if it's pushed down to the cracked versions automatically, add an update to the app that alerts the users that they bought a cracked version.  Inform them their copy is illegal, and will be disabled in X days.  Don't leave them out in the cold.  Offer a discounted rate to get a valid copy.  Something like 50%.  Entice them to become your customers.By offering a discount, and not just shutting them down the users will hopefully take it as a sign of good faith, and switch.  Some won't.However, their software is updating through you, so you have more control than the crackers, and they aren't going to keep buying it from them, nor get support.  They will realize if it's a worthy product, they are better getting it from you.As for preventing future purchases from crackers. Try and sneak in some 'unique' code into each version downloaded.  That way you can determine which person is buying your software and reselling it.  IANAL, so consult one, but it would aid the authorities if you chose legal action.Also, improve your authentication verification in the next version.  Leave parts of the app out, and require that they be downloaded at login.  Have some files encrypted, and require they go to your server to be decrypted.  The more you make the crackers have to do, to crack, the better.