In the science of Hadith, how can it be known whether a narrator described as "trustworthy if he narrates from his book and errs if he narrates from memory" narrated a specific hadith from his memory or from his book? And should acting upon the hadith be suspended until it is confirmed that he narrated it from his book?

The narrator's taking from his book, and not from his memory, is known by several indicators: that the narrator explicitly states he took it from his book, or that Hadith scholars explicitly state that this narrator transmitted in one instance from his book and in other instances from his memory, or that Hadith scholars explicitly state that no one took from his book except so-and-so, in which case his Hadith is accepted through this channel, or that scholars of defects ( العلل) explicitly state that the Hadith is not in his book.