There is no limit to the number of users that can use one headband. Each user just needs to set up an individual account on their mobile device or tablet. If you are using one mobile device or tablet, you just need to sign into/out of your account to switch users. To sign out of the app click on the ‘settings’ tab and scroll all the way to the bottom of the screen then click on ‘sign out’. It’s important for each person to have their own account. If one account was used by multiple people it would cause the brain data to be inaccurate and skew each person’s results.