my @Logwerte = (
  { Name => "Name1", GAs => ({GA => "GA1", columnName => "A"})},
  { Name => "Name2", GAs => ({GA => "GA2", columnName => "A"},
                             {GA => "GA3", columnName => "B"})},
);

# log each group address
foreach my $element (@Logwerte) {
  foreach my $GAelement ($element->{GAs}) {
    plugin_log($plugname, "subscribe for GA [$GAelement->{GA}] and columnName [$GAelement->{columnName}]");
  }
}