I did it.

sub {
my $tags = shift;
my $table = $DB->table('MyTable');
my $num_days = $tags->{ExpirePeriod};
my $date = time - (86400 * $num_days);
require GT::SQL::Condition;
my $cond = GT::SQL::Condition->new( 'CreationDay', '<', $date );
$table->delete( $cond );
return;
}

Paul