Even though your particular split between upfront + recurring costs is different than in my example, it's still in the spirit of sustainability. I honestly have

Even though your particular split between upfront + recurring costs is different than in my example, it's still in the spirit of sustainability. I honestly have no idea how the economics pan out if you had $50 app and $X yearly upgrade (or is it $X for 1yr of updates?) compared to, say, $20 each 1.5yrs. But in both cases, I think you'll have a chance of building something that can last. Interesting stats about the lifetime upgrades - thanks for providing those. I guess it works as long as all of your users don't buy it (which means your recurring revenue drops to 0 at some point and you're back to square one).