The trial version has no limitations. But if you would like to use HarePoint Password Change for SharePoint after the 30 days evaluation period, purchase and registration is required.
There are two licensing models for HarePoint Password Change for SharePoint:
1. Server-based licensing
In this case the object of licensing is Web Front End server (WFE). You need to license all WFEs in your environment. The number of users is unlimited with this model.
2. User-based licensing
This model allows you to license the software based on the number of SharePoint users - you can purchase as many licenses as many users you have.
SharePoint user - is a user authorized some way on the SharePoint server.
The number of user licenses should be equal to the number of authorized users who have access to the SharePoint portal. There is a limitation for minimal available license - 50-user license in this licensing model.