Logic Pro 9 Serial Number Killer!!


I was trying to update Logic 9.0.0 to 9.1.1 which worked out fine. I then tried to update further to 9.1.8. It worked, but it asked for the serial number. Well I bought my 2007 mac pro tower with Logic 9.0.0 installed, thus I do not have the serial number. So I called Apple. Eventually I agreed to purchase Logic X but I had to update my OS to 10.8.6. Well the 2007 Mac Pro will not update to Mountain Lion. Thus no Mountain Lion, no Logic X and hence no Logic Studio.
So I am looking for alternative ways to open my current version.

Furthermore, I have a serial number for Logic 9.2.0 from my laptop but that serial number does not work.

Can anyone help? How do I get around this issue? I have 4yrs of mucis on my computer. Thanks in advance.