Toll-free links (TFL) are keyed URLs that allow for free access to anyone clicking the link. JEM uses these in Tweets about Legacy articles and will request the keyed URL when needed. TFL are set up in Sitemanager as shown below.
First, choose the journal, then under production Management, click Toll Free Links
Find the article by DOI
Click create link
The resulting link is displayed and ready to copy and paste