Same developer, so you get a head start. A SQLPro Studio license takes 50% off Hydra Dev Studio; any other SQLPro license takes 25% off. Enter your key and the code is yours, on screen and in your inbox.
The key you activated the app with (it starts with S2, S3 or MACOSLT), and the address to send the code to.
One code per license. Each code works once and does not expire. Your address is used for this one email and nothing else.
Bought SQLPro before 2020, or through the Mac App Store, and your key is not recognised? Email support with your purchase details and we will sort it out by hand.