I have been in the hosting business for almost 10 years now and I see this over and over again, domain names expire without the owner's knowledge. Letting your domain names expire can be costly. Once your domain name enters the "Redemption" period, it can cost upwards of $200.00 to get it back. Worse, it can be claimed by domain name squatters.
Here are some of the things to keep your domain names up to date!