When you purchase a domain, you can set it to auto-renew or not auto-renew. If you want to make sure you keep the domain, set it to auto-renew and keep a credit card on file. If you fail to renew the domain, the domain goes back on to the market. You may not be able to get it back. Use a solid email address when purchasing a domain. Don't use a school email address. The domain name reseller will notify you when it is up for renewal, and if you miss the renewal, you will lose the domain.