Claudio Augusto De Paulo Resende
I have had a problem to register my trial license of a theme,
when I try to register by control panel I just receive the error
"Server encountered an error. Please try again"
when I try to register by Liferay's web site, I put the IP and MAC address and nothing happens.
​​​​​​​ Does anyone have any idea which can be? Thank you in advance

You probably got this theme from Liferay's Marketplace. Look up the author/vendor next to the theme page on marketplace and contact them. They'll be able to help you. At a minimum for help here, we'd need to know more details than "a theme".

Hi 
thank you for your reply, I was going to delete the post, because I was considering silly, but maybe is not, so I will leave my resolution.
The problem was because I got a old liferay instalation, so ended up that someone already had used that lisence, I just had to cleaned up de directory
Liferay..../data/lisence

kind regardsm
​​​​​​​Claudio Resende