Allow users to pay for your product via Stripe Payment Link.
You can place the payment link on any website.
When a user pays, a webhook will be sent to the Rails app.
The webhook will grant the user access to a private GitHub repository.
Start selling your code now!

Based on this blogpost:
https://blog.corsego.com/github-api-collaborators
Episode source code:
https://github.com/corsego/175-github-api/commit/f739888032d4e2af64f56b2efa49eeb05ff79e80

Stripe gem:
https://github.com/stripe/stripe-ruby
Github API gem:
https://github.com/octokit/octokit.rb