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How to Load an ARX Plugin in AutoCAD (APPLOAD, Startup Suite, Trusted Paths)

Published Oct 10, 2026 · 6 min read

An .arx file is a native ObjectARX application — the same kind of add-in AutoCAD uses internally, and the reason tools like CadMemFree can work directly on memory. Loading one takes about a minute. This guide covers the three supported methods and every error we see in support.

Before you start

Match the year. CadMemFree ships one build per AutoCAD version: freemem_2017.arx … freemem_2027.arx. Pick the file matching your AutoCAD year exactly — a 2024 build will not load in 2026.
Unblock the ZIP. Right-click cadfreemem.zip → Properties → tick Unblock → Apply, then extract. Windows blocks downloaded files, which is the #1 cause of silent load failures.
Check the flavour. Works with AutoCAD and all verticals (Architecture, Mechanical, Electrical, Civil 3D, MEP, Plant 3D incl. P&ID, Map 3D, Raster Design, Advance Steel). Not AutoCAD LT, and Windows only.

Method 1 — APPLOAD (load for this session)

Type APPLOAD in the command line.
Browse to the extracted folder and select your freemem_YYYY.arx.
Click Load. You should see the file listed under Loaded Applications.
Type LICENSE. If the command is recognised, the plugin is running.

This lasts until you close AutoCAD — perfect for a quick test.

Method 2 — Startup Suite (auto-load every session)

Type APPLOAD.
Under Startup Suite, click Contents.
Click Add, select the .arx, then Close.
Restart AutoCAD — the plugin loads silently on every launch.

Recommended for daily use, and it survives profile changes better than a one-off load.

Method 3 — Startup folder or a bundle

For managed deployments, drop the plugin into a folder AutoCAD already trusts:

User plug-ins folder: %APPDATA%\Autodesk\ApplicationPlugins (use a .bundle for cleanest results).
Or add the folder to Options → Files → Support File Search Path and load it from acaddoc.lsp with (command "_arxload" "C:/path/freemem_2026.arx").

Stop the “File not loaded / untrusted source” warning

Modern AutoCAD refuses to load code from paths it doesn't trust. Do one of the following:

Open Options → Files → Trusted Locations and add the plugin folder (best option).
Or set SECURELOAD to 0 — this disables the check entirely, so only use it temporarily on a machine you control.

Verify it works

Type LICENSE. It should display your Machine ID and a 14-day trial status.
Type REGISTER [email protected] if you want the free tier registered to you — no purchase required.
Leave AutoCAD open for a while: idle memory is reclaimed automatically, and you can run a manual clean whenever the session feels heavy.

Troubleshooting

“Unknown command” when I type LICENSE

The ARX didn't load. Check the year mismatch, the Windows Unblock flag, and whether the folder is trusted.

The file loads but nothing happens

You probably loaded a build for a different AutoCAD year, or the same file is already loaded from another folder. Run ARX → L to list loaded apps and unload duplicates.

Can I use it on AutoCAD LT?

No. LT does not support ARX or any programmability beyond LISP in recent releases.

Does it need admin rights?

No. Everything runs in the user profile; no installer and no registry writes outside AutoCAD.

After installation

Once loaded, CadMemFree gives you 14 days of full features, then 10 automatic cleans per day plus 10 manual cleans — free forever. One paid license covers up to 3 PCs and every AutoCAD version on each.

Grab the package and try it today — download CadMemFree free or see pricing.