Factory Security, Immobilizers and Reprogramming.....
This doesn't apply to everyone, some vehicles need no reprogramming or reflash at all.
They are simply plug in and start it up. However some vehicles do have factory security
with an immobilizer system that will not allow you to use a replacement ECM,
without dealng with the immobilizer via replacement or reflash. 
Our remanufactured units all originally come from another vehicle at some point.
They are rebuilt in regards to the circuitry, which restores the proper function,
it has nothing to do with memory or reprograming.
We do not reprogram, reflash or "clear" units, we physically repair and or replace components on them,
to make sure they are functioning properly and have a long life.
If your unit has to be reprogramed to operate your vehcle,
that final step will have to be done on your end, after it is installed in the vehicle. 
Not all vehicles have ECMs that need to be "reflashed" or "reprogrammed", its important that you find out before you purchase a unit that may have to be taken to a dealer, repair shop or locksmith for reprogramming. 
We do offer in many cases, the purchase of the imobilizer, ignition and key if needed, to accompany replacement computers for vehicles that require that type of installation process in order to function properly.