Obtain new library files (usually in visageSDK/lib) (.dll, .so, .a, .lib) and overwrite the old ones in your application
Obtain new header files (usually in visageSDK/include) and overwrite the old ones in your application
Obtain new data files (usually in visageSDK/Samples/data) and overwrite the old ones in your application (models as well).
Read about the changes in parameters of the configuration files and apply them to your configuration. In case you use default configuration, just overwrite it with the new one.
How does visage|SDK handle privacy? GDPR compliance?
Regarding GDPR and privacy issues in general: visage|SDK runs entirely on the client device and it does not store or transmit any personal information (photos, names or similar), or even any other information (other than Visage Technologies License Key File, for licensing purposes).
Languages, platforms, tools etc.