Wai There are three types.
Managed products - Managed items that can be purchased only once per user account on Google Play. Google play permanently stores the transaction information for each item on a per-user basis.
Unmanaged products - Unmanaged products are not managed by Google Play. You are responsible for managing the transaction information and cannot query Google Play to retrieve transaction information.
Subscription - Subscriptions let you sell content, services, or features in your app with automated, recurring billing.
I have a 'managed product', so it can only be bought once. So you would need an unmanaged product to sell it multiple times.