How to do a secure license check?

Question

JavaScript

hello everyone,

I'm making software based on licenses, and I just can't decide how to do it, since this is my first project using licenses.

structure:
1. my software will be installed on the client servers, it is written in Node.JS and will be compiled using the pkg package (client servers will be on ubuntu).
2. on the license server will also be in which it will be checked whether this License Key is valid.

the conditions are as follows:
1. on the client server, if the Internet program is disconnected, it must continue to work (even restart the server)
2. if someone uses the same, that is, already used key, then the software should not start

because of these conditions it is not possible to come up with something adequate, maybe someone will advise how to act in such situations.
thanks in advance

Answer 1

Well, what's the difficulty?
take a broken JetBrains and copy from them how often they check the license, if there is no imagination
(2) it will not work instantly, but right after the check - easily