How can I get more than just 2 dual cores when using my standard Parallels?

I want to really add more CPU cores to my machine as I Have a lot of it to spare with my Mac-book Pro, but because I am using a purchased Version out right than subscribing a monthly cost, as lately I can't afford it, is there a way, to outright get a pro version or even a way to unlock more cores, as it runs really slow with just 2, and as stated before, with limited funds, I can't really afford a monthly subscription, which is why I bought the Home Standard Edition, or am I missing something here. Please help a confused member, as I tried contacting support a while ago about something else, and they never responded.

-HikaruT