Citation, Documentation of Sources
Q. How does Chicago recommend citing a URL that is only accessible via a paywall? I’ve noticed the practice of including a parenthetical statement “(subscription required),” but I haven’t seen Chicago address this.
A. You can find examples of citations of such materials at CMOS 14.271. Although our examples don’t include information about subscription, add it if you think it will be helpful to your readers. Beware, however, that noting it in one case somewhat implies that all sources have been checked for accessibility. That might oblige you to recheck all the sources.