diff --git a/archive/index.md b/archive/index.md
index cbccfe9..faa8bdb 100644
--- a/archive/index.md
+++ b/archive/index.md
@@ -2,3 +2,7 @@
 
 The Archive SDK allows for working with various archive formats, ZIP, TAR, etc. on the JVM. The standout feature is
 strong encryption support for ZIP files.
+
+## License key
+The Archive SDK requires a license key. Contact [PKWARE Sales and Support](mailto:sales@pkware.com) for your key if you
+don't already have it. Existing code samples require you to provide your license key.