Hello @Chris Wood,
Welcome to the LastPass Community!
I hope this message finds you well. I apologize for the inconvenience this is causing you. I will like you to check under Account Settings > General > Advanced settings > Security > Auto-logoff > set to 2 weeks and Bookmarklet Auto-Logoff > set to 2 weeks. Then go to the extension > Account > Extension settings > General > Security > Verify that you don't have any option you don't want or need for auto-log out.
Then follow these steps to start fresh new:
Note: Before taking any of these steps, please make sure you know your master password!
1. Clearthe LastPass cacheandrefresh sitesfrom the LastPass extension, log out
2. Proceed touninstall the LastPass extension, and clear cache and cookies (all time) on the browser. Remember to verify if the browser is up to date if it's Chrome check under Settings > About Chrome.
3. Close completely and reopen the browser,install the extension again, log back in, and verify if the issue persists
If the issue persists verify that your browser is not clearing cache and cookies automatically or check if you are not using VPN which change your IP every certain amount of time and might log you out.
Kind Regards,
Alejandra
LastPass Support