Jeep RKE , Remote Key Entry, FOB , transponder types.   

First off the FOB has 2 chips inside, one runs the door locks, the other allows you to start car (transponder way) (a.k.a., the immobilzer)
The battery in my fob runs the door locks only.
The transponder cell, seen here below, uses no  BATTERY AT ALL, "no wires"  is uses the ENERGY of the 125khz RF signal (or higher) as the chips power source. (just like toll road tags do, only the frequency and power levels are huge there) AKA RFID. to some.
Seen here; (a good example to see how she  works is the glass type). My WK jeep chip is black plastic, no fun looking at it.? Mine uses the Philips ID 46 chip PCF7936 Crypto 2 transponder chip.

This glass ampule, has what ? , oil inside or a  liquid that does not expand at say -40F,  a coil antenna, and the electronics chip inside it.
The  cars key slot antenna feeds a (radio freqency) & RF receiver there, and a diode bridge rectifier module, that creates the power source inside the ampule, in 39mS max.  (fast) It wakes up now and the chip here, talks to the ignition WIN module reciever.
The rolling encrpyted passwords transmitted, are not crackable by any one.  Bingo car starts. IMMOibiler is happy. IMMO lamp goes out. Engine can now run longer that 3 seconds...  My local locksmith programmed 3 extra keys for me, for $75 (labor)

My JK 08; jeep I can make up to 6 more spare keys  if  the origional 2 still work, yes, takes 2 to make 3rd or more. (the 8 key max rule is hard and fast., but yes, the dealer can reset this too, or even block old lost keys)
The free operators guide in the glove box told you that and I read it and it works. 100% perfectly.
Rule 2, the key can not be used from another car, (yes, there are some cars and fobs that can be erased using locksmith $1500 tools (go there and ask) a "FOB transponder programmer" (some can be cloned, that is correct. you can have two keys numbered as 1's... pure cloned identical.) saving like $300 at dealer too.
One could have 8 factory fobs and 8  more clones of those 8.   (keep in mind most cloning programmer MAY not make the key lock buttons work , at this time, I'm  sure this will change. but you need to ask the man programming your key /car)
 One could make a clone fob, just to get engine started, and use the metal key to get in to car.... (has value)   I also have 2 working POD keys for both my Jeeps,  that are sold for $5.(no buttons on them!) Pods make a great backup key to the expensive origional.
There are like 50 chips used inside FOBS, and which one you have I don't know, but some have different rules.... (no one can answer this,  but do your own research and learn what chip you have and what it can and can not do? It is fully documented in eg. "data sheets"

WK:  ("FOBIK")
My WK 10'  Jeep you can never DIY program the new FOB (called,  "FOBIK") yourself,  now.... (some locksmiths can do it or even be able to clone the FOB)
The new Real JEEP factory FOB is $68 to $237 (stealerships are just what?, that ! (google the p/n online and this is true)   My 4 botton is # 68066848AD (no remote start option)  Do not guess , find out the correct key to get, there are  4 to 6 different keys, based car options.
The cloned hardware  FOBs are $20 sold in vast numbers of stores (not made by jeep), some are very good in quality.   $5 POD keys, or $45 ful FOBs can be had cheap.
You can also buy fob shells for $15 and put the old working guts into  the new case and now it looks good and no gummy keys.
The owner of the  this WK JEEP can buy 2 POD keys for $10.  They have no door buttons, but you can cut the key , then program it and drive all  you want. (best is to have a 2nd normal key and 2 POD keys  as backup, to save cash and future GRIEF)

I'm told the ID46 chip can not be cloned.  But there are execptions, some times , a transponder programmer (tool) can clone your key to only there blanks,  ask your locksmith (local){ there are folks every day trying hard to find ways to hack into keys, and updating programmers...
So that may mean  only the $20,000 dealer STARSCAN system works.  (there are starscan clones too... see MicroPod-II below)
I bought an after market  full fob, 4 buttons, for $35 and 2 POD keys for $10(a pair) then my local lock smith programmed all 3 to work for a flat $75.   (Me? not one trip to any  Stealership, shop since 1975 Magnuson-Moss Warranty Act, was passed.)
Avoid, the $5 dirt cheapest imported FULL FOB's, as some do work ok ,but the case falls apart in your pocket. (true knockoffs do that,  if not engineered correctly)
If you have one working  FOB or better 2, then buy any fob brand and programm it (learn it) and try it,  If it works use it as an emergancy backup. 
As always, if  a fob buttons act odd,  try a new coin cell  battery inside, if that don't fix it , then clean the button contacts inside with alcohol.
There is a factory TSB , on this FOB warns of tiny cracks inside it (a PCB) that are caused by using the key with huge sets of keys below it, (don't torture your FOB)
The best price $68 on real Jeep WK FOB, was found this way. $115 is the average price (2015)

Wild questions and answers.
Erasing old keys,  some keys can in fact be erased, say , from another car,  using the a special programmer , but some chips can be erased and this service is sold on ebay or directly for about $10-50 each.  YMMV.  Many keys can not be erased, by design.
Unplugging the car battery will not erase any codes, or passwords in the key or its recievers.
Removing the fob battery will not erase any codes, (makes door locks go dead, until good battery is replaced)

More programmers:  The Dmax tool does older (<2006) non rolling code keys. 
The Micropod II does the newer Jeeps.$2000+ tool  with 1yr license then  $1000 to $2000 annual license fees at TechAuthority. (no way ,can you do that many keys at that price and make money,  a 53 key break even?)  That is where clone tools win. (no pun on Win)
What if key is good but the WIN module is dead, what if the RF field was dead.?
There is a cheap tool sold , that measures the SKIM, or WIN  ignition antenna  RF power  field (transponder RF field), such that if it dead?, If the FIELD is dead so be all keys.
This nice simple tool is called an RF field tester, that can be as simple as and Antenna, RF diode and and LED. As seen here.

end tip of iceberg.

rev 2   ++++ 10-3-2015