Can I use license key with brand label on other computer

First of all hello, im new here, and second sorry for my terrible English grammar :p * I have a Dell laptop with Windows 7 Home Premium Dell (not oem, but with dell brand name on it) license and label. My laptop died, and i bought new custom pc, witouth any license, can i use my old dell license on new pc? * And second question, if i dont have any purchase document only license label, can i...