I would modify the script to display a notice:

"Thank you for using SortTable from https://www.kryogenix.org/code/browser/sorttable/. If you, the site owner, would like to use SortTable without this notice, please download the script from [here](URL link) and add it to your server."

If you want to get fancy you can serve the modified script only if it's being hot linked and the original script if it's being used on www.kryogenix.org - or another website that has permission to use the script.