I think NAG falls into a similar category as magnesium in terms of Lyme. Yes, you may feed a few bugs, so you have to decide if the benefits outweigh the risks. In the case of magnesium, it is fairly straightforward because magnesium is so critical for other life functions.
With NAG, the choice is a little harder and really depends on your individual circumstances. First, are you in a good Lyme treatment program? If you are treating actively, I would feel safer adding supps like this.
Also, do you have the conditions the supplement is meant to help with? I think that the benefits of NAG in autoimmune disease and on the function of T cells may also be worth the risk.
Conditions that affect the GAG layer, or recurrent sinus or other mucus membrane infections might also be a good reason to try it.
Then just add up the pros and cons...and give it a try.
I took a bottle of it and noticed no effects one way or another unfortunately so I stopped it.