The below thread is another classic example of how to alienate your paying clients.
http://forum.parallels.com/showthread.php?t=258991
"We use in-product notifications to share several types of information with our customers. First, and most importantly, we share information about product updates which are generally related to compatibility with OS X, new features and product enhancements. Second, we occasionally share special offers from Parallels or other third party companies who provide special deals for our customers. Many of our customers rely on the information about product updates and appreciate the special deals for products that are of interest to them.
Individual notifications can be turned off by clicking the “don’t show this again” button. However, because customers need to receive important product information, there is not a mechanism for customers to completely disable notifications."