Theory #2: Nathan sells drugs
This one is a bit of a stretch, but you might remember in episode five how everyone took Molly at Coachella. While Nathan’s friends were willing and ready to take the drug, Nathan showed some initial restraint.
Possibly a dealer who didn’t want to use his own product?
Eventually, Nathan took the drug along with Issa, but the whole scene does make you wonder how much drugs play a part in Nathan’s life. Some prior run-ins with the law definitely could have kept him away from Issa and this whole Lyft investigation.