Sorry for the stupid maybe even obvious question but i have to know.
There is a folder that comes with music creator that you can import music from. Are these just for example? or could i theoretically use them for commercial use? also if i have an electronic keyboard(PSR E423) do i need to use the music center? or is it unecessary?

Welcome to the forum.
Yes, you can use the included samples for any song/project for any reason.
No, you don't have to use the music center (Sound Center?) software synthesizer or any other soft synth if you don't want to. I use a lot of the sounds from my Yamaha keyboard in my songs. 

Welcome Daniil,
 
Everything in MC is there for you to use in whatever manner you so choose. You have the license to MC so you have the rights to use everything in it as your own. Same goes for any third party software synths and samples you may purchase to use with it in the future.
 
I have an old Yamaha DX-27s. I use it mainly to trigger the samples that are played by Cakewalk Sound Center (CSC) instruments. While I could choose to record the actual audio out from the 27s I prefer the much better sounding samples in CSC. So yes, I use CSC all the time when working with synths.
 
You are free to use MC in whatever manner you choose so if the sounds in your keyboard are preferable to you, use them, in which case, no, you don't need to use the CSC at all. You can record the midi into a midi track and send it back to the keyboard to play it's hardware synth while recording it's audio output to an audio track.

thanks!!!