An APK (Android Package Kit) is the file format used by the Android operating system to install apps. Standard APKs come from official sources like the Google Play Store.
A modded APK cannot change the server’s response. At best, a "free premium APK" might change the visual interface —showing you the premium buttons as if they were unlocked—but when you try to use the feature, the server will block you. At worst, the APK is designed to steal your data. Okcupid Premium Free Apk