Logging in to flow creates multiple sessions being used. This can be an issue for PM accounts because there are a limited number of licenses available, and each session will count for a license being used. In this scenario, a user logs in to Flow, their session timeouts, the cookie duration length has not expired but when logging in again, two (or more) sessions will show as logged in, therefore using up two licenses as shown in the image below:
To see the logged users in Flow, you will need to be logged in with a Project Manager or Admin account and go to Flow > Administration and the Logged Users will be in the Utilities section: 

There are several different ways that one user can account for multiple sessions being used simultaneously, here are some of them:

• If the user logs into Flow on different browsers. For example, being logged in to Flow on both Chrome and Edge at the same time will create separate sessions and use 2 licenses
• If the same user account is used to log in to Flow from different machines
• If any version of Internet Explorer is being used (which is no longer a supported browser) and the "Start with tabs from the last session" option is enabled in the Internet Options
• When opening multiple private (incognito) tabs, each one will account for a new session.
• If the Flow server or service is restarted when there are active sessions

To address the duplicate sessions due to the cookie length, a change can be made in Flow > Administration > System Parameters (Security Tab) and modify the "Session Extension cookie length" value to match the "Session Timeout" value for the Project Manager role. It is important to note that the Session Extension cookie length should not be less than the "Session Timeout" length.