I just got another order and I am inundated with liquid. Most of them I am not concerned about as they are flavors that I dislike. I do, although, have a 60ml/60mg bottle of unflavored PG that is about 3 months old. I can't see myself going through it anytime soon as I prefer VG juices. How long will this stuff keep (VG, PG and 50/50)? Will temp and light control help with the longevity? And, how do I tell when the juice has gone south?