Add to Chrome.
Click 'Add extension' above.
The installation process should take less than a minute.
Next, you'll Create an Account.
Why does my browser indicate that LastPass has an invalid or expired security certificate?
Most certificate warnings are caused because your PC's clock is not set correctly. Verify that your clock is set to the correct day, month, and year and retry.
If you still experience the issue, then your PC may have had its default list of certificates modified in some manner. Many employers change the standard certficiate settings to allow them to have greater control over what sites employees visit and in some instances to allow them to monitor all HTTPS traffic. Please check with your network administrator to determine if this is the case.
If you have tried all of the above, then please go to https://support.globalsign.com/customer/portal/articles/1426602-globalsign-root-certificates - and download the GlobalSign R1, R2, and R3 certificates. Then restart your machine and retry.
If you are using Windows XP be sure you update to Service Pack 3 - it contains the ability to utilize SHA-256 certificates