The process of enabling passwordless login will depend on the device you’re using to access LastPass:
Desktops:
Log in to your vault, open “Account Settings” and find the “Passwordless Options” tab: LastPass Authenticator, FIDO2-certified biometrics, or FIDO2-certified hardware keys. Click the option you prefer and follow the instructions. The next time you want to access your vault from your trusted device, you’ll be able to do so through passwordless login – without entering your master password.
How to enable LastPass Authenticator app for passwordless login
How to enable desktop biometrics for passwordless login
How to enable USB security key for passwordless login
Mobile phones:
Log in to the LastPass app using your email address and master password. Tap Settings and then Security. Enable passwordless login: Android users will turn on logging in with biometrics, while iOS users can log in with either Face ID or Touch ID (fingerprint). The next time you want to access your vault from your trusted mobile device, you can do so through passwordless login.
How to use passwordless login on mobile