Three reasons:
1. The app stays simple
— A one time subscription puts pressure to add ads on the app, restrict features (such as the history view, export, import) on a paywall to compensate for the unpredictable revenue. Given how simplistic an app like Spoons is, this is unnecessary and ends up downgrading the experience by locking features for no reason just to force you to pay.
2. Allows the mission to scale properly and be sustainable over time
— An autism adult diagnosis for one person is $2,000–$3,500, sometimes even more for certain metro clinics. (Up to $5000) One time purchases at a reasonable price (such as $20) puts constant pressure to monetize (Such as add ad's) and severely impacts the long term sustainability and longevity of the diagnosis fund for Spoons, gradually reducing both the quantity and quality of diagnoses funded.
This also impacts the long-term safety of me being able to run this properly, because if I can’t afford to live or maintain Spoons as product, how am I gonna fund any diagnosis at any point?
3.Lifetime codes planned for individuals diagnosed with support of Spoons
Lifetime codes are planned for individuals who's evaluation is paid for by Spoons, and diagonsed proves that they are autistic.
The code can be used at any time, forever.
Obviously charging those of us who went through an exhaustion process just to get answers, regardless of wether it was paid for or not, is not a very respectful thing to do in my opinion.
Note: With this being said, I am still considering lifetime purchasing options very soon, as most of us including myself are obviously "subscription-fatiqued" and would prefer to own Spoons completely, and if Spoons can't sustain itself financially for any reason, they app would be free anyways.