Password Reset Server is licensed per managed end user. For example, if there are 10,000 users in a Domain that need access to reset their password then you would need 10,000 user licenses. If you only need 4,000 users to be able to reset their password then 4,000 user licenses would be needed.
Yes, user licenses may be applied to the same instance of Password Reset Server at any time. Licenses with different effective dates can be co-termed into one annual renewal date.
Technical Support and access to upgrades is included as part of the annual fee.
No. Password Reset Server licenses may only be used on one production instance of Password Reset Server. You may, however, use your licenses on an additional test or staging instance (many customers use this to test new versions before rolling it out to their users).