Starting with 126.96.36.199/188.8.131.52 the Nero Digital features require a seperate Nero Digital product key.
Oddly enough, starting with 184.108.40.206 there is no need for DVD-Video plugin, Multichannel, or LAME MP3 Powerpack keys anymore. If you have Nero 6 Ultra, you have those features.
Ahead seems to change what features need their own keys with every release. This is more of a pain to legit users than anyone else.