Apple AppStore in-app purchases and auto renew subscriptions

I require assistance implement in-app purchase features using auto renew features.
- Setting up subscriptions in App Store connect.
- Implementing Objective-C code to process user subscription requests and change requests.
- Implementing Objective-C code to check on subscription level, which will control feature availability.
- And anything that I need to understand.

Please send details of expertise & experience, with App store link to an app you have development with subscriptions (if available).

Work will start with 1-2 hours of consulting.