1- First, go to your Apple developer account the, select your application
2- In the “In-app Purchases” menu, click on Manage and then on the “+” button
3- Choose “Auto-Renewable Subscription”.
4- Add a name for your plan (Reference Name). Ideally, choose an evocative name in the language covered by the geographical area of your offer.
For the product ID, choose a unique code of your choice. You will have to fill it in when you create the offer in the OKAST Editor (SKU id fields)
5- If this is your first configuration you will have the option to create a subscription group. A subscription group consists of subscriptions with different access levels, prices, and durations, so that users can choose the option that best suits their needs. Since users can only purchase one subscription at a time within a group, creating a single group is the best practice for most applications, as it prevents users from accidentally purchasing multiple subscriptions.
6- Click on the “Create” button
7 – Finalize the settings for your integrated purchase such as subscription duration, price, and languages. For the duration of the subscription, select 1 or 12 months.
How to set up a free period for your integrated purchase subscription?
You can add a free period to your subscription, for that in the section “Subscription price”, click on the “+” button
Choose the countries concerned, the dates of availability of this offer, then choose “Free” and finally set the duration of the trial period:
Click on “Done” to finalize your trial period. If you have more than one offer you will have to start the process again for the different offers.
Finally, you will also have to set up the pricing plan of the applications in the OKAST editor: Offer management > Subscriptions / Bundle (see this article for setting up)