They Do NOT re-activate!
I had Parallels 8, bought Parallels 9 and installed on my Mac, reformatted when I got new OS (the reason I upgraded from 8 to 9): tried to install and it will not activate. Asked support if they could reset the counter: they demanded either a story or more money. STAY AWAY FROM THIS GREEDY FARCE.
I AM NEVER BUYING A PARALLELS PRODUCT AGAIN:
I will write add-ons for VirtualBox or another virtualization platform to successfully and flawlessly replicate the convenient feature set of Parallels like folder sharing and coherence. It is not a difficult task: but I will give it away for all for free. I promise to spend my own money on SEO and Google AdWords to distribute the freeware solutions I create. 
If we don't go through life with a smile, something is wrong...!
Last edited: Oct 17, 2013