Yes, you need to purchase Enpass on every platform independently. It’s because your purchases on every platform are managed by the respective stores and are not available across the apps (even between iOS and macOS). Apple has stated this in their documentation as “Every product is associated with a specific app. Products created for use by one app are not available in other apps. Companion apps on a different platform are different apps—the products of the Mac app are not available in the iOS app and vice versa.”. So technically we cannot fetch and verify the details of your purchase on the platform over the other.
Being offline password manager, Enpass doesn’t require you to sign-up and create an account with us, using which we could have restored your subscription on other platforms.