I've hit that a few times with customer implementations. One of the first things I do when putting a new deployment together is to add another CLI user with role admin. When customers call me with this issue, I can generally login with my second credential and reset the admin password.
And yes, the admin account will expire in keeping with your admin access password policies. You can see those in the GUI and on the CLI.
If you do not have a secondary account at the CLI like I mentioned above, you'll need to go through the password recovery process. Here is a URL that will help: