Testing
Testing an application that bills, without reaching a payment provider.
Troubleshooting
Every exception the package throws, what it is protecting, and what to do about it.
Upgrading
What each release changes, and which changes need action before you deploy.
Migrating from Cashier
Moving an existing Cashier installation across without reissuing documents or losing history.
Migrating from your own billing code
Replacing hand-rolled billing, and the order that keeps money correct while you do it.
Selling works to consumers
What the package tells you about a purchase, so you can label it correctly — and what it deliberately leaves to you.