Because an IPA file only modifies the client-side code (the app on your phone), it cannot alter data on Netflix's servers. If you do not log in with a valid, active account, a modified IPA will not allow you to stream premium content. At most, a modified app can change how the user interface looks or how the video player behaves after you log in with a legitimate account. Risks and Security Warnings
Emulating the 6-device download limit reserved for the highest official tier. Risks of Using Modded IPAs netflix premium ipa exclusive
The Shadow Economy of Streaming: A Technical and Market Analysis of "Netflix Premium IPA" Distribution on iOS Because an IPA file only modifies the client-side