Save the Join info for Power off Device

Hi, Im using a RAK811. i need to do just one Join to get all the info and save it in non volatile memory , for example:
LoRaMacAppSKey
LoRaMacNwkSKey
LoRaMacNetID
UpLinkCounter
etc…

Then, the device will power off for a while, after that i need to read the memory to use the same info and do an uplink.

It’s possible ?
Im using: https://github.com/RAKWireless/RAK811_LoRaNode/issues/5