Is there a function in C++ that can get timestamps which cannot be changed? (internet independent)

I am looking for a function that I can implement in a standalone C++ application to gather timestamps from a user's computer that they cannot change by modifying their system time. The goal is to enforce yearly subscriptions.

The application must be able to function internationally (so no standardized time zone), and cross-platform (so windows, IOS, Android, etc.) and the unique challenge here comes from needing this functionality regardless of whether the user ever connects to the internet past downloading the application.

Functionality within the C++ standard libraries would be preferred. Does anyone know if this is possible within C++ alone, or if there are functions in the Windows, IOS, Android, etc. libraries which provide this?

The users of my program are highly educated, and changing their system time/shutting off their system when not using the application to extend the life of this application is within their grasp.

Thanks