diff --git a/solvespace.cpp b/solvespace.cpp
index 6ebd9c3..ed54e3e 100644
--- a/solvespace.cpp
+++ b/solvespace.cpp
@@ -29,6 +29,13 @@ void SolveSpace::CheckLicenseFromRegistry(void) {
     const int SECONDS_IN_DAY = 60*60*24;
     license.trialDaysRemaining = 30 -
         (int)(((now - license.firstUse))/SECONDS_IN_DAY);
+
+    if((!license.licensed) && (license.trialDaysRemaining < 0)) {
+        Message("The 30-day demo has expired. All exported content will "
+                "contain a message noting that it was generated by an "
+                "unregistered version of SolveSpace.");
+        OpenWebsite("http://solvespace.com/buyunreg");
+    }
 }
 
 void SolveSpace::Init(char *cmdLine) {