: For versions 4 to 5 years back , such as 2018, you can use the Autodesk Assistant (the question mark icon in the bottom right of your account page) to request a download link if your subscription is active.
Autodesk does not produce or endorse portable versions of AutoCAD LT. True "portable" software runs from a USB drive without installation — this is technically impossible for AutoCAD LT due to: download AutoCAD LT 2018 portable 64 bit
: Students and educators may be eligible for free access to certain versions through the Autodesk Education Community Free Trial : For versions 4 to 5 years back