SOOS trial accounts allow a maximum of 5 users.  Once a trial account is converted to a paid subscription account a maximum of 1,000 users are allowed.

Note:  A user invited to access the SOOS App is not necessarily the same as a Contributing Developer represented by the number of "seats" purchased with a subscription.  Not all Contributing Developers may have user access to the App, and not all App users may be Contributing Developers.  See What is a 'Contributing Developer'? for more information.