The short version, because there is not much to disclose:
- Your workbook never leaves Excel. Marks, sign-offs, legends, and reports are written directly into your file on your device.
- The add-in’s only network request is validating your license key. On the free tier it makes no network requests at all.
- Your key, settings, custom marks, and custom image marks are stored in your local Office add-in storage only.
- No analytics, no cookies, no advertising, no automatic error reports.
The full document is the Audit Tickmarks privacy policy; the terms of use are here.