Hi All. LastPass by default keeps the browser extension logged in for two weeks (14 days) before having the reauthenticate. The options in BitWarden only go up to 4 hours. I have been forced the select ‘Never’, which I don’t want to do. I like the 14 day safety net to ensure if I no longer use the device, and forget to remove it from BitWarden, that it cannot login at a later date.
It doesn’t refer to the exact date you want, but 2FA works that way. For 30 days, that is.
Otherwise, you’ll be locked out of your vault, depending on the 2FA method. But about the master password logout, no. However, as far as I’ve seen all data is securely saved in RAM and encrypted at all times.
It’s more complex than that, but that’s just a TL;DR. I can provide you the sources to check if you want, but later. Now it’s nap time here. 
Actually, it appears this is not entirely true. The Bitwarden mobile and PC apps and browser extensions do not logout after 30 days. See my post here:
I am not sure if this is a bug or intended behaviour - there isn’t much info about the expected behaviour.