Where do you place the API Key for TinyMCE?
Well quite simply like this.
<!DOCTYPE html>
<html>
<head>
<script src="//cloud.tinymce.com/stable/tinymce.min.js?apiKey=your_API_key"></script>
<script>tinymce.init({ selector:'textarea' });</script>
</head>
<body>
<textarea>AllSupported.com - answers for everything :)</textarea>
</body>
</html>
For more information on how to use TinyMCE Cloud edition check out the documentation here.