Unlocking
Type your passphrase on the unlock screen and press Unlock. To use the recovery key instead, choose Use the recovery key instead and type the key from your sheet.
Locking
Choose Lock vault at the bottom of the sidebar at any time. The vault also locks itself after a period of inactivity — 30 minutes unless you change it in Settings → Security → Lock after inactivity (5 minutes to 2 hours).
A minute before it locks, a countdown appears above Lock vault; moving the mouse or pressing a key keeps the vault open.
When the vault locks, everything decrypted is dropped from the screen and from memory — open dialogs, lists, photos, even a half-finished edit. You are returned to the unlock screen.