diff --git a/aws/README.md b/aws/README.md
index e689a06..b573fa3 100644
--- a/aws/README.md
+++ b/aws/README.md
@@ -10,6 +10,7 @@ You can also use `t2.micro` instance as your server for your deployment, which i
 
 - AWS EC2 Instance Type
 - OS for your VPN Server (Ubuntu16.04, Ubuntu18.04 or Debian9-stretch)
+  > **Note:** To use Debian9 on EC2, to need to [**subscribe**](https://aws.amazon.com/marketplace/pp?sku=55q52qvgjfpdj2fpfy9mb1lo4) first.
 - Your VPN username
 - Your VPN password
 - IPSec PSK (pre-shared key)
@@ -57,4 +58,4 @@ Copyright (C) 2020 [S. X. Liang](https://github.com/scottpedia)
 
 ## Screenshots
 
-<img src="specify-parameters.png" alt="Step 2">
\ No newline at end of file
+<img src="specify-parameters.png" alt="Step 2">