I highly recommend using pen or pencil on paper and not using anything digital. The paper will last for decades, just roll your finished drawings into a tube and put them away for ten years, then revisit them or frame them and send to friends.
Ideally, digital drawings will last for just as long too!
But I'd like to do that. I bought a binder and some paper protectors. It might be ego and vanity here, but I'd like to record my entire progression if possible.