There are many options to restrict content views on CDN and therefore protect it from unauthorized views from the user side. For example, it may be done based on geographical principle. Usually IPs of end user incoming requests are checked. Those IPs are compared to the typical blocks of IP addresses assigned in certain countries (states in the USA). In case the end user IP address is not on the list of restricted IPs, it is allowed to access content from the servers of the content delivery network.
Often it is possible to add countries in allowed list and and countries to restricted list. There is no limit on such limitations. Often special codes are used to define countries.