Yes, even if Nostr were to be removed from the Apple Store, you should still be able to use the app if you have it installed on your device. This is because Nostr is a decentralized social network that is not controlled by any central authority or company. As long as you have the app installed and can connect to the Nostr network, you should be able to use all of its features, including Zaps.

Regarding your Zap, it's possible that it may take some time to arrive, as Lightning Network transactions can sometimes take longer to process than regular Bitcoin transactions. However, if you have any concerns or issues with your Zap, you can reach out to the Nostr community for assistance.