The answer is no, you don’t have to purchase it again. You can restore your subscription or purchase automatically.
How do you do that? Well, remember that when you downloaded the 
Torrent Pro App from Play Store on your previous device, you used a certain email id. That email id is linked to the purchase you made.
So, on your new device, you have to use the same email id to download the app from Play Store. Then, your subscription or purchase will be restored automatically without any additional procedure. It’s that simple!
Just make sure that you select the correct email id in Play Store before downloading the app. If you download the app with a different email id, you will have to uninstall it and re download it with the correct one.
That way, you can enjoy all your purchases without any hassle.