I guess you purchased the VDH/Chrome license before February 1st 2021. This means your license is managed through the Chrome Webstore. In that case, there is no license key/number per se. The fact you are premium is based on the fact you are logged into Chrome using the same account you purchased the license from.
Starting on February 1st, Google ended their Chrome Webstore payment services, so licenses are now handled by our servers and are based on a key, like we do for many years on Firefox and more recently on Edge.
From your side, the fact you have an old or a new license does not change anything and i can generate a new license for free if you want. However, licenses are browser-type specific and a license for Chrome won't work on Firefox or Edge. Regarding Brave, we do not have licenses for this browser anyway.
Note that if you run Linux instead of Windows, you can use VDH on Firefox, Edge, Chrome or Brave with full premium privileges without the need for a license.