virtual currencies must only be used within the app where they were first purchased. In-app purchases (Monetization and Ads) https://play.google.com/about/monetization-ads/
in-game currencies purchased via IAP must be consumed within the app and may not expire, and you should make sure you have a restore mechanism for any restorable in-app purchases. 3.1.1 In-App Purchase https://developer.apple.com/app-store/review/guidelines/
in-game currencies purchased via IAP must be consumed within the app and may not expire, and you should make sure you have a restore mechanism for any restorable in-app purchases. 3.1.1 In-App Purchase https://developer.apple.com/app-store/review/guidelines/