Idea of Software Encryption

How to encrypt software
Generally, software in the C/S architecture is divided into two parts: client and server.
The software installed on the client machine is generally only a client. Therefore, we only need to add a validation table on the server side and a serial number field in the table.
When the client is installed for the first time, determine whether the serial number exists on the server. The Web service can be used for this verification.
Of course, what should I do if the network is disconnected?
You can encrypt the serial number and save it to the local file on the client.
Then, except for the first time that the client wants to connect to the server-side database, you only need to determine whether the local serial number is correct.