The Dongle must remain inserted into a USB slot on your computer in order for the software to remain registered. If all of your USB slots are being used, there are two ways to add more USB slots.
The first is to use a USB hub. This is a cable or box with 2 or more additional USB slots that plugs into your computer, expanding the total number of USB connections.
The second is to add a USB card to your computer. If you are not comfortable installing internal hardware into your computer, you may want to ask a computer technician to do this for you.
Either of these items can be found at a computer store, or online at places like www.cdw.com or www.tigerdirect.com, usually starting at around $20.