Starting an Arnold trial - Arnold User Guide
Fill out the form here to get a trial license. You must click Download to generate the trial license, but you can cancel the download.
Open the Arnold License Manager (in the Arnold menu for your Arnold plugin, click Licensing > Arnold License Manager)
If you don't see a Single-user tab, click License > Switch to Single-user Licensing
If prompted, install single-user licensing and register Arnold.
Click Sign In and enter your Autodesk ID and password.
You'll see the status of your trial license. Happy rendering!