Use JavaScript SetTimeout
It will show you the alert message after one hour
Ref:
http://www.w3schools.com/jsref/met_win_settimeout.asp
<html>
<body>
<p>Click the button to wait 3 seconds, then alert "Hello".</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
setTimeout(function(){alert("Hello")}, 3600000);
}
</script>
</body>
</html>
Demo