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

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