Hello @robinsfiddlegarden
Welcome to the community! my apologies for the delay on getting back to you on this.
If you're still looking to improve the security of your extension you can modify the security preferences to be logged out after certain amount of minutes or when browser is closed, you can review this article: Change General preferences for the LastPass browser extension.
If you need further assistance or have any more questions do not hesitate to contact us back or submit a case to support: Contact Us.