Earlier quoted context omitted.
What would be an appropriate price?
I don't care too much about the price. I'm happy to pay a premium for great software that I use almost all the time. I would not subscribe to anything recurrent though.
I think a subscription model can work if done right. It’s unreasonable to expect work on software to be free (and great if it is, like with so many open source programs and libraries), but it also isn’t okay to require payment in perpetuity just to use the program. With these in mind I think models like Sublime’s or Sketch’s are the right balance.