Simple question: Say that I have Magento comunity installed in two diferent hosts. One for development porpouses, and the other will be the real store. If I buy an extension, can I use it in both? or it is licensed just for one use?
I don’t see why there would be a problem, but just to be sure check with the extension developer. The majority of extensions are created by 3rd party developers. If you go to the extension under Magento Connect, there is a developer profile and a way to contact them.
It is possible that they can be locked one per domain, but what you’re doing with a live and development version isn’t out of the ordinary and I would hope that our 3rd party developers could accommodate that.