LT Toolkit from the now-defunct drcauto was an add-on for AutoCAD LT that provided LISP and other capabilities that Autodesk disabled. Autodesk hated this, of course, but the late Gary D’Arcy made sure everything was done legally so it couldn’t be stopped even by Autodesk’s hyperactive legal team.
If you are a user of LT Toolkit and you want to keep using the software now the company has closed down, you may find this information from Evan Yares useful:
I’ve gotten in contact with Leonard Liang, the former key developer at DRCauto. He’s asked me to send any Toolkit Max users to him, and he will help them. His website is www.cadsta.com. His email, at that domain, is “leonardl”.
Source: a comment in this this WorldCAD Access post. If you don’t read comments, you may well have missed this, so I thought it was worth repeating.