Toyota Smart key - How many keys can be registred

[Weasel3]

Just a simple question. Tried Google some days ago, didn't find any good answer.

How many Smart keys can actually be registered into one vehicle. Toyota/Lexus

Had a case which I suspect that the total number was reached.
And this is why the key was not registered.
Or if the key, wasn't the right one for the model. Because this could also be the case.
But I am not sure though. I didn't try to delete and add again. Just tried to add the one I had new for a spare.

Is there any difference between years and models, regarding the total amount?
And also difference between US and International?

[ray-ray]

Most toyota/Lexus smart key max is 4 proxy

[Weasel3]

I read a place that the
FCC ID: HYQ14AAB

Is compatible with

FCC ID: HYQ14AEM

Anyone can confirm this?

And would it somehow work with 315,2Mhz CN, when it is supposed to have the 314,3Mhz US.
I suspect that the frequency does not supersede each other.

[super jumbe]

You only need 2 keys, if anything going wrong with immo all the keys are useless what’s the point having say 4 keys.

[ray-ray]

Fcc:AAB was first generation smart proxy Lexus or toyota... fcc:AEM superseded AAB and is backwards compatible..
it took place in 2006.