The Remote Authentication Dial-In User Service (RADIUS) protocol is used to provide centralized administration of authentication, authorization, and accounting (AAA) and an industry-standard security infrastructure. RADIUS is defined in RFCs 2138 and 2139 in the IETF RFC Database. RADIUS enables administrators to manage a set of authorization policies, accumulate accounting information, and access an account database from a central location.
StrongVPN is a great choice, as it meets the needs of both power users and casual users alike. Prices start at $10 a month and drop quickly, when you purchase a year of service at a time, to $5.83 a month. The ease of setup is fantastic–if you’re new to VPNs and/or don’t have extra time to fuss with manual settings, you can just download their setup app for Windows, OS X, iOS, and Android to automate the setup process. If you want a more granular control or need to manually configure devices like your router, you can follow one of their many guides for different operating systems and hardware to do it manually.
Most VPN services allow you to connect up to five devices with a single account. Any service that offers fewer connections is outside the mainstream. Keep in mind that you'll need to connect every device in your home individually to the VPN service, so just two or three licenses won't be enough for the average nested pair. Note that many VPN services offer native apps for both Android and iOS, but that such devices count toward your total number of connections.