Ford tech here, if the key you had was a regular turn to start key, and you had 2 of them programmed already, you could program a third key by yourself. But since the FiST is a push to start, the key fob must be programmed using Ford's IDS system. This can only be done at Ford dealerships. also, are you getting just the fob? there is a little key inside that is laser cut, so only certain delaerships can actually cut you a new key. The key is in case the battery dies and you cant get inside the vehicle using power locks.
Ok great info!! How about to program the Mykey thingy? I see that there is supposed to be a slot somewhere inside the car to place the fob for charging and for programming the mykey but i cant find it for shit.
Don't know if it is true, but many of the online key fob resellers note that you cannot reprogram it on your own, but a locksmith can do it, or the Ford dealer. One site notes that Ford dealers may often reprogram them for free. See https://ikeyless.com/vehicles/Ford/Fiesta+/2014/1004082/