So many people have asked that question recently, so here is the quickest solution to it. You don't need to download cracks & hacks for this.
STEP 1: Open Origin & hover over the game
STEP 2: Click the little "i" button, and copy the Serial there
STEP 3: Paste the key into a blank Notepad file.
STEP 4: Open the game and edit the Serial before logging in or when it asks you to on Multiplayer
STEP 5: Type your Serial you pasted in the Notepad, but use dashes "-" between ever 4 digits
(like this BLAH-BLAH-BLAH-BLAH)
STEP 6: It should work now!
If you can't understand this, then I'll try to translate it to a few languages. Good luck!