sub load_session {
...
        return undef;
...
}

And now consider my code: 
...
    $sid =  $cookies->{license_session}->value();

    # load session from db
    my $s = Mapps::Session->new();
    $s->load_session($sid);

    # session is good continue
    if (defined $s){
        $m->call_next;
    }

##</code><code>##

if (defined $s->load_session($sid)) {
   $m->call_next;
}