Refunds for nonfunctional iOS apps

Purchased Apps are licensed to you for use for as long as the Apps remain available, compatible and usable with your devices. Apps can be withdrawn, or become unsupported, by the respective App Developer at any time. Purchasing an App does not guarantee permanent ongoing update support for an App.

Apps being withdrawn, or losing update support, are not of themselves grounds for a refund. In some countries/regions, there is a short period of time after purchase to return software and request a refund from Apple. This facility exists not to permit trial of a software title, but to facilitate refund for an App purchased in error from the Apple App Store.

You can ask, but it's up to Apple whether they consider that having used them for some time you are due for a refund. Go to https://reportaproblem.apple.com/?s=6 and select 'Request a refund' from the menu in the page. Note that the refund, if granted, can take up to 30 days to be paid into the payment method used for the purchase - please see Check the status of a refund for apps or content that you bought from Apple - Apple Support