A frevvo' user is anyone that is authenticated to frevvo for the purpose of:
These are users that don't need an account in frevvo and also aren't involved in any of the items described above. Anonymous users do NOT count as frevvo users and therefore are not limited by the license. Common examples are filling out a survey or a contact form.
Concurrent users are frevvo users that are logged in to frevvo simultaneously.
Generally, for Intranet forms/workflows you want to calculate how many users will concurrently be accessing the forms, since in most cases, on an Intranet, people want to know who is submitting the form. For Extranet forms, you generally do not have authenticated users. For instance, a 10-concurrent user license means 10 users can be logged in simultaneously to frevvo.
frevvo also offers Unlimited user licenses.