Deanne,
Extender is an Additional Feature developed by eOne. It allows you to add fields, windows and other information to virtually any window within Dynamics. It had been licensed by Microsoft for distribution several versions ago. With GP2013, the licensing of Extender moved away from Microsoft and back to eOne. You need to contact your partner, they should have arranged moving your Extender license to eOne. eOne's ip address is http://www.eonesolutions.com/ You will need to contact them because you will need to download the product and get new reg keys for Extender to work.
Claude