Choice of KeeLoq_NLF encryption

Hi Renzo

I have some curiosities and doubts about the library.
Is the choice of KeeLoq_NLF encryption personal, or is it some encryption standard adopted by Ebyte, Semtech or LoraWAN?

Does using KeeLoq_NLF encryption increase the total size of the transmitted message?
Example:
struct MessageTemperature {
char type[5];
char message[8];
byte temperature[4];
};

MessageTemperature is 17 bytes, correct? When using KeeLoq_NLF does the message size in bytes grow?