How to implement a key activation system?

Question

Java

I am writing a project in java and need to create an activation system for the program.
Since I am not very competent in this matter, after flipping through a bunch of pages on the Internet, I thought that all the systematics would be built according to the plan:
1. The user receives the key and inserts it into the application
2. The application, having the decryption key, checks the key for validity
3. Received the data is sent to the server
4. The server processes and creates an encrypted response
5. The program decrypts this response and, depending on the data received:
- Creates a cell in the registry (hardware binding)
- Simply answers that the key is invalid
I think something about this plan is not right, but I can not understand what exactly.

Answer 1

Is it too difficult to store the key in the database? And bind to the user's account, well, control that only 1 person uses the account at a time?