If you already have a Premium account but you're getting asked to pay again, please follow these steps.
1. Open the Hotspot Shield App > Account, and verify that you’re signed in to the proper account.
2. Navigate to the Menu extra, and then click on Restore Purchase. For more information on restoring the purchase on your Mac device please follow this guide here.
The Hotspot Shield Account page should display your account info with account type as Premium and expiration date.