Thanks for sharing, I can't believe all this time I wasn't aware templates have {% extends %} and {%block ...%}.
Compared to the Candy Japan codebase, this code is cleaner, but seems only to be the sign-up part? I wonder if you have some extra scripts you run when fulfillment day comes.
But then what manages the plans? Where is the rake task that checks all the subscriptions daily to look for expirations and take action? Where is the functionality for recurring subscriptions? I don't see that anywhere in here.
https://bitbucket.org/lost_theory/flask-stripe-blueprint
It's meant to be integrated into an existing flask application (just override & instantiate the blueprint, then mount it on your app).