You could just use dynamic variables as well, for example:

on *:kick:#: { inc % $+ $knick }

Creates/increases the variable for that nickname.
you can do

on *:NICK:{ 
if (% $+ $nick != $null) { 
set % $+ $newnick % $+ $nick
unset % $+ $nick 
}
}

to account for nick changes that way