add LICENSE.

Signed-off-by: 葛峻恺 <202115006@mail.sdu.edu.cn>

LICENSE-COMMERCIAL.md

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+# Commercial License for GPR-SIDL-inv.
+
+This software is dual-licensed:
+
+- Under the terms of the [GNU General Public License v3 (GPL-3.0)](https://www.gnu.org/licenses/gpl-3.0.html) for open-source use.
+- Under the **Commercial License** for proprietary or commercial use.
+
+## Commercial Usage
+
+If you intend to use this software as part of a commercial product, service, or distribution and cannot comply with the terms of the GPL v3 (e.g., you do not wish to disclose your own source code), you must obtain a commercial license.
+
+## How to Obtain a Commercial License
+
+Please contact the project maintainers via:
+
+📧 Email: sunhuaifeng@email.sdu.edu.cn  
+
+📍 Organization: State Key Laboratory for Tunnel Engineering, Institute of Geotechnical and Underground Engineering, Department of Engineering Software, Shandong University, 17923, Jingshi Road, Jinan, Shandong, China, 250061.
+
+We will provide you with details of pricing, terms, and support options.
+
+## Summary
+
+| License Type     | Use Case                                | Notes                            |
+|------------------|------------------------------------------|----------------------------------|
+| GPL v3           | Academic, non-commercial open-source use | Must open source derivative work |
+| Commercial License | Proprietary or commercial use           | Source code disclosure not required |
+
+
+