You can add up to 4 profiles regardless of your subscription.
Adding profiles via the app
Tap the user icon in the bottom right corner. At the top of the screen you can see your profiles. If you have less than 4 profiles, you can tap "+Add profile" to add a new profile.
Adding profiles via the website
Log in to nextory.se. In the menu on the left, click on "Profiles". Click on "Create profile" to add a new profile. If you are already logged in to the website, click on the user icon at the top of the website. Then click on "Profiles" in the menu on the left.