Clarify license part

README.md

@@ -80,8 +80,8 @@ misinformation, as well as any associated data security concerns.
 
 ## License
 
-The **Yi** series models are fully open for academic research and free
-commercial usage. All usage must be adhered to the [Model License
-Agreement](https://huggingface.co/01-ai/Yi-6B/blob/main/LICENSE). To apply for
-the official commercial license, please contact us
+The Yi series models are fully open for academic research and free commercial
+usage with permission via applications. All usage must adhere to the [Model
+License Agreement](https://huggingface.co/01-ai/Yi-6B/blob/main/LICENSE). To
+apply for the official commercial license, please contact us
 ([yi@01.ai](mailto:yi@01.ai)).