When you purchase a Premium subscription via the iTunes Store, you can easily apply your Premium subscription to your account by using the Restore Purchases feature.
Before restoring your purchase, please:
1. Sign in to the App Store using the Apple ID that you used to purchase Premium.
2. Update to the latest Hotspot Shield version available in the App Store.
3. Sign in to your Premium account in the Hotspot Shield app.
4. Check the restrictions on your device to make sure in-app purchases are allowed: How to check the restrictions on the device
5. Check your purchase history in your computer to make sure that you were charged for the purchase.
6. Restart your device.
To restore a purchased Premium subscription:
1. In the app, tap on Menu button to open Settings.
2. Tap Restore Purchases.
3. Sign in to iTunes Store with your Apple ID password and tap OK.
4. Tap OK to confirm.
If restoring your purchase fails, please submit a request and provide a screenshot of your iTunes receipt email.
In case you have a free account, you can try an Premium account for free here.