FiveM client gta 5 copy id

Hello and thank you for the help.
My question is I want to know how can I get the client unique gta 5 copy ID just the same way as FiveM gets the identifier license. Is there a dll file that exports that function and I can give it a param of the path of the game or something like that I was searching the source code, but I could find anything. Any help will be helpful.

why would you need their gta 5 copy id?
identifier licence is all you need if you banning players or whitelisting…

identifier licence is the gta 5 copy I just want to access it without FiveM. My purpose is that i want from my server website the user to have the ability to change his characters data (money, buy clothers, etc) but as I know NEVER TRUST THE CLIENT so I can’t ask him to type his character name or something like that because I can’t be 100% sure that the character that he will choose will be his.