Why developer need to provide restore button?

Hi, I am working on Subscription when i saw the SKDEmo apple video, and many of the other developer statement is, need to provide Restore button.

My question is: App restore the subscription automatically using Storekit 2, then why we need Restore button and please explain what is the purpose of the button in Storekit 2.

Implement proactive in-app purchase restore:

continue providing a “Restore Purchases” button within your app. While not used often, it does give customers an opportunity to force an app to restore their Apple ID’s transactions in case of an issue or if the customer uses a different Apple ID.

Ok thanks for your reply, Which place is correct to show the Restore button, which means - I have one Purchase screen with buy button and also another screen after the purchase done it shows the expiry date.

Why developer need to provide restore button?
 
 
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