A deck’s ⋯ › Export for Anki… makes an .apkg of it; the shelf’s ⋯ › Export library for Anki… makes one of every deck, archived ones too. Open it in Anki (File › Import on a computer), and it carries:
- the cards as you edited them, with their pictures and sounds;
- when each is due, and which are suspended, flagged or marked;
- the review history.
In Anki, the cards use two note types named RectoVerso and RectoVerso Cloze. Their last field, also named RectoVerso, keeps what Anki has no place for: how much of each answer you revealed, and the card’s memory. Leave it as it is: bring the file back to RectoVerso later, and the deck comes back with its history, including what you studied in Anki.
To bring decks in from Anki, see Importing from Anki.