Before qt.io was announced I wrote support and asked the same question. In short - yes, you have to pay each month according to them. It's quite reasonable perhaps except for apps that are updated very rarely.

Yep. Only the really-expensive commercial license comes with a permanent license.

We used to have one. It's such a pain in the neck to have to jump through hoops and deal with salespeople for every very-expensive renewal that we stopped renewing. When we want to update next, we'll just use the LGPL version. Opaque licensing plus sales people who don't even have the advantage of being able to negotiate on price is just too much stupid to bear.