Samsung IAP supports Credit Card by default in countries where Galaxy Store becomes a paid service.

Phone bill, PayPal, Samsung Pay and local payment methods (such as Shetab , Wechat , Alipay , Paytm) are available in some countries, except several Middle Eastern countries.

For more details, see the Galaxy Store Seller Portal

No, not for mobile phones.

However, non-Samsung devices paired with Galaxy Watch wearable devices via the Galaxy Wearable app can use Samsung IAP.

For details, see Galaxy Watch In-App Purchase.

Samsung IAP manages setting up an IAP instance, getting current in-app item details, and item purchase and payment processing.

Your app is responsible for followings:

• The logic to display items for purchase.
• Initiating item purchase.
• Managing all prerequisites and errors.

In-app items can only be sold in countries where paid services are available (currently over 120).

Galaxy Store must be installed on their device. They must be signed into their Samsung Account, which must have an acceptable payment method registered to it (such as a credit card).

Galaxy Store publishes free and paid apps that offer in-app items. However in Galaxy Store Seller Portal, you register your apps and in-app items, submit them for review testing, and manage them after they pass and are published.

No, Samsung IAP has only offered auto-recurring subscription since IAP 5.0 version.

After one period ends, the next period starts automatically, until the app user cancels their subscription (at any time during free trials or paid subscriptions).

Server to server verification is supported.
For details, see Verify a purchase.

It provides a way to identify each in-app item, and ensure returned purchase details are for a specific item.
If your app specifies a passThroughParam string value when initiating an in-app item purchase, IAP returns the string along with the purchase response details.

No, the returned list of product details is not guaranteed to be sorted.
However, your app can sort the list.

We strongly recommend that you use the provided IapHelper to prevent unexpected issues.
Otherwise, you must implement the complex logics that Samsung IAP offers such as the flow for Samsung Account authentication, the logic to communicate with Samsung Checkout and all processing.

If an item purchase is interrupted (for example, due to a battery or network problem), call getOwnedList() and check if the item is listed, which means the purchase was successfully completed.

If your application sets to OPERATION_MODE_TEST mode, the subscription cycle is automatically renewed every 10 minutes and the subscription is automatically canceled after 12 renewals.

Whether Galaxy Store users can download you app for free or after paying an app purchase price:

You must have a commercial Samsung Seller Portal account because all in-app items must be paid for by app users. In-app items can only be sold is countries where paid services are available (currently over 120).