Resolution
No, you do not. If SUS ( Software Update Service ) on your current license key has not expired you can upgrade the key for free. If one year of SUS is over then the key will be updated for a fee. More price information you can find on our official site:
http://www.parallels.com/en/buyonline/support
Additional information
Please refer to following article
http://kb.parallels.com/en/456 for more information about SUS.