I shouldn't have included the font licensing fee (and in fact have since edited the article to remove it). Our annual server fees are 15-20x the cost of the font license.
What I was thinking about was opening sourcing the app. If we do that, we'll have to replace Ideal Sans with another font. The obvious choice would be iOS's system font.
That's hardly a showstopper. They could easily remove the proprietary font when open sourcing. I doubt the heavy users of this app are using solely because the font is beautiful.
The font is not cheap either*.
When you can barely get people to pay $0.99 for a industry leading app, how on earth can you justify paying so much $$ for a font. I mean switch to the closest google / open source version and call it good enough.
It's $300/year from what I can see. Not free, but if you think it's a valuable part of your design, a small cost, unless you just don't have a viable business in the first place.
"The biggest factor is that we have recurring costs: the sync server and the licensing fees for Ideal Sans, Vesper’s typeface."
They'd need to continue paying for their font license.