You can turn off the power button functionality in Windows by going to Power Options -> you current plan -> change advanced options -> Power buttons ans lid. Change it to do nothing.
Your computer will still turn off if the button is held down for 5-10 seconds, but it should protect you from your cat accidentally hitting it.
You don't have to buy it, it's free. However, the version you have installed is most likely an old beta, they are made to stop working after a specific date. Download the latest version from the website, currently version 4.0.0 is the latest.