By agreeing with these terms of service you agree that the application is allowed to store content of metadata for messages which invoke the bot. Metadata includes guild name, username, and discriminator. The application is completely open source, so you always are able to see what data is exactly being stored.
This data is not shared with anyone. It is used only for the developer to debug issues with the bot and know whether it is still being used.
If you still don't want to have this data stored, contact kangalioo#9108, and all your data will be deleted and stopped from being logged.