On your iPhone you can check / search easily.
Go to -> Settings -> tap your profile -> tap Media and purchases -> View account -> log in.
Scroll to and tap -> Purchase history -> tap the last 90 days.
You will then see a list of 'years' and you can select a year to view.
To request for a refund, it is depends on when you purchased the app.
You must request the refund within the refund period (thought within 90 days).
You can try to -> Request a refund for apps or content that you bought from Apple.
Request a refund for apps or content you've bought from Apple – Apple Support (UK)
If you have requested a refund, you must wait until Apple has approved. Then you will receive a message from Apple.
Refunds are not guaranteed. For more information, see the Terms & Conditions.