When you initially set up your Dashlane account to work with 2FA and YubiKey, you specified the level of security you wanted to use. That means that the YubiKey works with whatever security level you specified. If you specified that you want to authenticate with your YubiKey only when adding a new device, you will not be prompted to touch your YubiKey each time you log in. If you want to change this security setting, so that you are prompted to touch your key each time you log in, you will need to disable 2FA in Dashlane, and then enable it again to change the setting. For more information, see the Dashlane help.