Dynamic IP Update Service is simply a way of attaching a static hostname to a dynamic IP address. On the Internet, there are a limited number of IP addresses. When you connect to your ISP, you are assigned a temporary IP address that other computers use to find you while you are connected. Once you disconnect, that IP address is given to someone else, and so on. Dynamic IP Update Service automatically updates your IP at the dynamic DNS service.

DDNSServ is a fully featured server suite that allows you to run your own DDNS (Dynamic DNS server). You will have the ability to set trial periods, and pricing for your users. You could offer the service free of charge or take advantage of the built in registration and payment processing features.