You should manually go through an copy all of your important vault information into a new Bitwarden account as soon as possible, because client apps can sometimes get logged out without warning (in which case you will lose access to all of your vault data).
Always write down the master password before you even enter it into BW, to be kept in a safe place. This is always one thing to do regardless of anything else.
Some people store their master password in BW, either directly or as an obscured entry, then this scenario wouldn’t be a problem, although they probably need to be religious in locking BW. Another way is to stored the master password in an encrypted form, keeping the password in BW. This step shouldn’t preclude doing 1).