Help!! - can't use Parallels on my Mac

I have a permanent key for Parallels Desktop for Mac 9.
I assume I should still be able to use it to run Parallels? Each time I try a dialogue box pops up with the words "Unable to start Parallels service... if problem persists contact Parallels support"
Do I need to upgrade? If I upgrade do I need to buy a new licence?
If I'd have to pay for the upgrade, can I just use Parallels 9.

 

Make sure your Mac OS X is compatible with Parallels Desktop 9. If it is then you can continue using Parallels Desktop 9 else, you need to purchase full version of latest Parallels Desktop.