Adobe Creative Suite 6 family Master collection

My creative suites softwares stopped working about a year ago and asked for my serial number (which at the time I couldn't put my hand on them as I recenlty moved and they were somewhere in a box...) I finally sorted through all the boxes in the garage and found the original box, disk and serial number. How do I apply it back to my software, since I've been paying a monthly fee for the past year? I dont use the software enough to justify this reoccuring cost, just want to be able to use my software as I used to. Thanks for any help