How many keys will a 2006 or 2007 Honda Accord accept

Actually, three has been the constant limit, for all standard alarm and/or factory keyless entry....Code Alarm, and DEI, unless very special, have allowed 3 fob frequencies to be recognized... good Lord how many more can you need for a single vehicle?

Also, you can put that fourth remote on the system....and chances are, it will bump one of the first three programmed remotes, off the system recognition.

THANK YOU for your information and advice in this! Sincerely. I will settle for having 3 keys fully programmed into the car for both igntinon kill and door/window opening (yes, I am very well aware those are two different things mediated by two different electronic means... RFID vs an actual battery-powered remote control coded transmitter). Just as a friendly footnote, as I see it there are many perfectly valid logical sound reasons for SOME people (not the majority, but SOME) to want 4 (and in some cases 5 or 6) keys to a car. In my case the car is owned by a close friend. I keep a third key for her, for I sometimes need to move her car when she's not around. She benefits from having two spares in addition to the one she routinely uses, so if she loses one she has another handy, and can feel comfortable lending a key to other friends of hers who she occasionally has drive her car when she's out of town. There are easily 6 or 7 people who have ability to unlock my two residences, for I often have a friend stay at my place when I'm not there, or have my contractor come by to do work when I'm not there. For my residences I have switched over entirely to using high quality commercial grade (KABA brand) kepad locks, instead of mechanical key locks. These allow for up to 100 different codes, and let me add or subtract a code any time, avoiding the embarrassment and social awkwardness of having to ask someone to return their key if I need to end access to my place. They also allow me to give access to someone when I'm far away, by just looking up spare codes I've programmed in, and giving them out when needed (via voice phone for security... I tend to avoid texting or using email for this).

More information: (1) My friend has FOUR master Honda keys for her 2006 Accord (all black, with built in remote door lock / unlock powered by a CR1620 cell) that ALL WORK FINE to start her car. BUT... when I try to program the remote contol part of the key using the "chicken dance" instructions one finds all over the internet, I can successfully program ONLY TWO of these. After proraming two of the remote doors, the car refuses to recognize more. I can program any given two of the four door remote systems to work (I put fresh CR1620 coin cells in all of them and all have the red LED light up brightly when you push a button) BUT cannot program more than two to be working with the car. Durn. Anyone have anything to add?

There is too many keys that have already been programmed before probably by the previous owner(s). In order to add your new transmitters you must delete/remove the stored old ones in the system's memory. An automotive locksmith can do this for you.