Go to the Sign up to Once page, and enter the total number of users that you want to be able to use Once Mobile or Once Track.

e.g. If you currently have a single user subscription and want to have 4 users you must enter 4 for the number of users.

For full details on adding/reducing the number of Once Mobile users, including the changes you need to make in Once Setup and how it affects your subscription, take a look at the article on our Support Portal.