I've been trying to find the answer to this question but so far have had no luck. Where is the remote key ecu located? Is it in the main ecu unit? can it be taken out?

I'm getting ready to sell and swap my ECU but still want to keep the remote key function. Are there any other functions that I could possibly lose? (the ecu units have the same serial number)

 

the remote ecu is behind the passenger side rear panel.