An NCH FAQ states...
"Can I move the software or reinstall the software in future?
Within reason - yes. As long as the software does not continue to run on the old computer you can install the software on a new computer. As a piracy control measure we do limit the number of installations to 2 times in any 12 month period.
Note: we do run an anti-piracy system which can detect multiple installs. But as long as the software (with one serial number) runs on one PC at any one time, you will not have problems."
For registration issues see...
https://www.nch.com.au/kb/10053.html
https://www.nch.com.au/support/reg.html