Hello paulcav and MattHollands, thank you very much for your replies.
paulcav, thank you for such complete answer, this helps me a lot, it is very easy to integrate.
MattHollands, you are using the RFM69 for "listening" for those key fobs, or you are suggesting using the RFM69 for creating a 433MHz link? if is for creating the link it is not good for me, I would like to use the already existent key fobs because they are cheap and can easily transported in the pocket.
Best regards, Mauro.