Read https://openiap.dev/docs/types/ios/subscription-period-ios and https://openiap.dev/llms.txt. Follow the reading instructions, detailed reference, and linked guides relevant to my task before making changes.
Inspect my existing project and reuse its framework and conventions. Ask me for missing product decisions. Implement the requested behavior and run the applicable checks.
Show the working result, the commands and actual test results, and any remaining limitations. Keep your explanation brief.

My request: [describe what customers should be able to do]