To keep it active every time you open AutoCAD, use the APPLOAD command, then click the button under the "Startup Suite" section (the briefcase icon) to add the file permanently. Using the Command Once loaded, follow these steps to measure your objects: Solved: New tlen.lsp for polylines - Autodesk Community
Always be careful when downloading .lsp files. Since they are script files, they can theoretically contain malicious code. Only download from reputable CAD community forums or trusted developers. autocad tlenlsp download work
If you want, I can: