Create an instance object of the {Configuration} class (using New_read_config / New_write_config functions) to store / restore some values by the application. This is a multiplatform solution. In Windows, if a key is opened with the 'USER' privileges and a Path parameter is not set to HKEY_..., then a prefix HKCU\Software\ is added to the Path automatically. When opened with 'ADMIN' privileges, same way HKLM\ is prefixed if there are no HKEY_ in the start of the Path parameter.
It is possible to use Value_i / Value_s / Value_b as bi-directional functions to set new values and get old values at a time.