For some time Opera has offered a free version of their VPN (Virtual Private Network) for iOS devices. Soon it will no longer be available. Following is an article that discusses this:
It's expensive for any company to maintain a VPN network, and unreasonable for them to offer it free. How can a company afford to do this? The desktop version of the Opera Browser does continue to offer a free built-in VPN, but I'm guessing Opera is doing this to try to increase market share for their browser. How long they'll continue to do this is uncertain, though.