howto increase 50 domain limit for admin ?

This is very easy.
That is a virtual limit that is in effect up to version 0.28
You may set it as you wish in phpmyadmin, ehcp db, panelusers table
go to that table, edit admin user, set maxdomains as you wish.. set maxpanelusers and soon...

After version 0.28, i will set that 500 as default...

in fact this is a virtual limit, to protect your server...