I am trying to figure out how to protect php application and doing a license for php applications, do you have any idea of what is the best ?
Best would be to try the verify-purchase api call to protect items sold through this marketplace.
Probably have to figure it out how to protect it in some way yourself, because if someone posts a how-to here it would be easy to reverse it.
Nothing is 100%, anyone who knows php can get around any sort of protection that can be sold on these marketplaces.
Otherwise if you are making a program not for sale on this marketplace, and you don’t want the client to access the code, then http://www.ioncube.com/ is the best commercial way to go.
Make sure hosting environment supports ioncube.
I think a lot of the big guys like plesk and cpanel use this to protect their own source code / licensing system.