Ghost License Question?

If i have a license for Ghosty on a computer and have to reimage that computer do I need to purchase a seperate License for that computer? 

Same computer but hacve to reimage for virus so i want to reload the image that was created for it. Do i need to repurchase Ghost License for that computer or can i just reload the image on the computer. 

Also if i want to bring the image down to a computer and do windows updates that doesn't count as a new image created does it?   Wondering