Apologies as we're not sure what troubleshooting you've tried so far, have you already tried uninstalling the LastPass extension and reinstalling from here then testing again? https://lastpass.com/download/
Yes, your LastPass Vault data is not stored on your device specifically but is stored securely in the cloud. If you log out or uninstall/reinstall LastPass or log in to LastPass on a new device your Vault data will be shown as soon as you log in.
First, I'm not using Chrome, I'm using Safari. I uninstalled and reinstalled Lastpass and the Lastpass Safari extension and yet I am unable to activate the safari extension. It is not showing up when I go to Safari - Preferences _ extensions. It is not listed. I have quit safari and reopened it 4 times. Nothing. Any suggestions?
Could you double check that you have the LastPass Mac App downloaded from here: https://lastpass.com/download/ (the LastPass mac app includes the safari extension)
I did download it from there, uninstalled and reinstalled 2 or 3 times. I spoke with support at LastPass and after trying several things to fix the problem, the person I spoke with confirmed that there is a known problem with the latest version of LP not working with the latest version of Safari, so I have switched to Firefox. Thank you for your help!
There is still a LastPass Free option, to see features for each of the LastPass plans please see this page: https://www.lastpass.com/plans-and-pricing