LH uses the new menzies/servisair lounge ath the schengen side of the airport. They used to use the old BMI-lounge which became the old servisair lounge and is now closed.

The new menzies/servisair lounge looks nice but offerings are meager. Limited alcoholic beverages / softdrinks and nothing much of food except crisps, cake and apples. Sometimes they do manage to present slices of cheese or a salad bowl.

I always hoped that there would be a star alliance lounge in AMS in both non-schengen and schengen side as the netherlands is served by:
non schengen: SQ, UA, US, CO, MS, OU (and BR -maybe future *member-)
schengen: LH, LX, LO, OS, SK, JP, TP

But i guess the rent might be to high or KLM/Schiphol is heavily guarding their dominant position.