By default, the LastPass icon turns red (dark gray in Safari) when you have logged in and will turn gray (light gray in Safari) when you have logged off:
To log in using the LastPass plugin, click on the icon and enter your Email and Master Password in the dialog box. Note that the icon is grey here since it is logged out:
If you use more than one LastPass account, you will be presented with a dropdown menu to select the account you would like to use to log in. If you wish to delete any saved email addresses, click the ‘X’ next to the email field. If you do not have a LastPass account, please click the “Create an account now” link to get started.