A plan is an offer, subscription a customer agreement, entitlement a permission, and payment a financial event.

How to apply it

Centralize entitlement evaluation using plan, subscription status, trial, add-ons, seats, grace period, and overrides. Define behavior for trialing, active, past due, paused, canceled, and incomplete states.

Worked example

A central feature-entitlement service resolves access to audit exports rather than repeating plan-name checks across controllers.

Common mistakes to avoid

Scattering plan conditionals or treating a checkout return URL as proof of payment.

Practice task

Implement this concept in the capstone. Add one positive test, one negative or failure-path test, and a short note explaining the trade-off you chose.