On the iA blog, Oliver Reichenstein argues that apps are more like coffee makers than the cups of coffee to which they are always related.

If there is a valid coffee comparison it’s the coffee maker. Productivity apps are not consumed. Productivity apps are tools. They help you make things. Great apps help you make nice things. Pro apps help you make pro things. How could a text editor compete with an espresso machine?

Since I don't buy a daily cup of coffee, I never got the frequent comparison of subscription prices to cups of coffee. It's overused and doesn't provide context for many people. I think the suggestion that a writing app is equivalent to a coffee maker is a better analogy. Which ultimately means, a piece of software makes more sense with a perpetual license like that which is employed with iA Writer.