You should have access to your serial number via the MyAccount section of the https://www.finalemusic.com/ web site.

If you can open your copy of Finale, it should be listed on your About Finale panel (accessible via the Help menu in Windows & IIRC the Finale Menu on a Mac) but probably only once you have registered/authorized that copy..

that's not help me, I cant find anything . i went to my account. i cant find about finale 

It should be listed under your registered products: the name of the program and, below it, the serial number.

Not meaning to be rude or anything, but you did buy the product, right?

What version is it? How did you get it? On a disc, or by download?

Work from college? If you used your school’s site license, you might not have your own license. 

Other than that, my questions are the same as MikeR’s.