If so does the nic level just go down and how long after the date can you still vape it?
Echoing what Ryedan said. Also, keep in mind what PG and VG are, they don't really 'expire' per se. So why then have an Exp date? Simple. FDA rules and regs. Anything that is 'food/medical quality' which the PG and VG has to be to be legal in this situation, must be stamped with an expiration date. I mean Ramen Noodles, Canned Goods, and even -VINEGAR- has an Expiration date! And Vinegar doesn't expire, PERIOD. Same with Honey. It's just silly rules by the FDA is all. I'd really pay no attention to the dates what so ever, and just go by what you smell/taste!
I recently got back into vaping after a three and a half year hiatus, so I am a good test case. Seventeen bottles of ejuice, all 3-4 years old. All kept in a cool dark pantry on the bottom shelf. One bottle had gotten quite a bit darker in color and another had separated into two layers. The other 15 were exactly as I left them, tasted the same and I can vouch for the potency of the nic...if it has degraded I can't taste of feel the difference.