Is it possible to use a keyless remote entry with a Maxima which didn't originally come with one?

I am not sure if mine did or not, I just got a single key when I bought it. Is it a part of a standard package? This car is base GXE without any extras.

 

I would suggest you ask your dealer. My car is 1996 GXE with the Comfort and Convenience package and it comes with it. I would expect a 1997+ to come with one standard. Maybe you should ask a seller on eBay - they should be able to tell you and there are a few up there. Just trying to help.