my $user = $justloggedin;
##</code><code>##

my $newcookie = $query->cookie( 
    -name    => 'arbitrarycookiename',
    -value   => $user,
    -expires => '+15m'); #no activity in 15min...gone!

my $user = $query->cookie('arbitrarycookiename'); #read it
if ($user) { $stillloggedin } else { &loggin() }