Cannot activate a purchased plugin (Opt-in Panda)


I’ve purchased Opt-in Panda some while ago and it always have been used on my only domain.
Some weeks ago I’ve noticed I was using the free version and my license key wasn’t unblocking the plugin.
It says:

The request has been rejected by the Licensing Server
The license key allows you to use the plugin on 1 domain(s). You have already activated the key on 1 domain(s). Please purchase another license key or remove the key for the domains where you are using it now.

Well, I’ve always been using on the same domain… and now seems like I can’t use it anymore, I don’t know why.
I’ve tried to reach the support by the comments page and also by their e-mail, but none answered me. I need a new key or someone who can put me in touch with the developer.
I’m really dissapointed with Envato for still letting the dev make sales on this conditions of support.