The introduction of a trade company based in Sansha, with a valid license, involves the following steps:

1. **Company Formation**: The trade company is legally registered in Sansha, which is an autonomous region within China.

2. **License Acquisition**: To operate as a trade company, it requires specific licenses issued by the Chinese government or other relevant authorities. These licenses cover areas such as import/export, taxation, and business regulations.

3. **Company Profile**: The trade company presents its detailed profile, which includes the name, location, registered capital, ownership structure, and main business activities.

4. **Publicity and Visibility**: Once licensed and operational, the trade company would actively promote itself through various channels to increase visibility and attract potential clients.

In summary, introducing a trade company in Sansha with a valid license involves legal registration, license acquisition, company profile preparation, and active promotional efforts.