Norton Utilities 16.0.2 license question

I use Norton Utilities 16.0.2. I had the 3 computer license. I was using 2 of the 3 licenses. I just purchased a new laptop and will retire an old laptop. I used the third license on the new laptop. Once I retire the old laptop in a few days how do I get the one open license back again, since NU will then only be on two computers again.