Subscription model reflects the ongoing and increasing value that the app provides. If Netflix only had x amounts of movies and you could only watch it once then a subscription model wouldn't make sense.

Mindset is designed to be used on a daily basis and we have been and will continue to add value throughout the lifetime of the product.

If anyone accidentally renews the subscription we'd be more than happy to refund it because it's not worth destroying a consumer relationship forever for $6.99 :)