Just wanted to give a quick post here, as I couldn't find any details before my flight.
I flew a domestic Aeromexico flight in business class (Classe Premier?) from the NLU airport.
There is lounge access - it is the lounge opposite gate 107 (called VIP Salon). Do not go to the other lounge near gate 108 - this is only for Priority Pass. When I asked them if there was an Aeromexico lounge in the airport, they said "no" - clueless!

The AeroMexico lounge is nothing to write home about, and not worth going IMO. Its shared with Amex card access, so it is super crowded. It doesn't have a view at all, is quite a depressing area. The food selection is minimal - just a few snacks. There is a bar that does serve alcoholic drinks, but service is super slow. They did have a good selection of beers when I was there, not sure about other drinks and spirits.