Step 1
Create Identifier
- First go to https://developer.apple.com/ and sign in with your account.
- Go to account and click on identifier.

- Click on + icon to create new identifier.

- Select App IDs and click on continue.

- Select type App and click on continue.

- Mention Description and Bundle ID for application, choose services you want to add to application and continue to create identifier.

Note that...
- In-App Purchase service is by-default enabled.

- Click on continue and we have created identifier for application successfully.