A decree absolute is the final order which concludes the divorce process. Your decree absolute certificate is the legal document you need to confirm that your marriage has officially ended, meaning you are free to marry again, if you wish.
You should therefore keep your certificate of decree absolute in a safe place as you will be required to show an original copy of it, to prove your marital status if required. It is also a good idea to keep a record of your court number so that, in the event you misplace your original decree absolute document, you can apply to the court for another copy by quoting the court number.