I have paid for the Pro version and when I try to update with iJoomla Installer I have the following message : "This license is invalid. Please contact us for more information!".
I have checked my license number and it is the same on my website and on my Jomsocial user account.
Everything looks good from here. Please edit your message and you will see a pink form where you can leave your login info. I'll check on your site to see what's wrong with the installation process.
Also, what you could do is to update the iJoomla Installer to latest version to see if it helps.