diff --git a/intro.md b/intro.md
index c01d3a8..dce2a18 100644
--- a/intro.md
+++ b/intro.md
@@ -71,7 +71,7 @@ Refer to [How to cite Argo data](https://argo.ucsd.edu/data/acknowledging-argo/)
 
 ## License for this book
 
-All the content in the Argo Online School is licensed under the [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/) (CC BY-SA 4.0) license.
+All the content in the Argo Online School is licensed under the [Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-nc-sa/4.0/) (CC BY-NC-SA 4.0) license.
 
 ## How to contribute
 
diff --git a/license.md b/license.txt
similarity index 99%
rename from license.md
rename to license.txt
index df7a870..4e636cb 100644
--- a/license.md
+++ b/license.txt
@@ -1,5 +1,5 @@
 ## License for this book
-All the content in the Argo Online School (AOS) is licensed under the [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/) (CC BY-SA 4.0) license.
+All the content in the Argo Online School (AOS) is licensed under the [Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-nc-sa/4.0/) (CC BY-NC-SA 4.0) license.
 
 Terms of Use
 Creative Commons Master Terms of Use