Phil over at the Logos Bible Software Blog gave some helpful tips on locked resources. The fact that you can search locked resources is pretty handy, though I’ve found that it is not a guaranteed thing. For one, as Phil noted you have to own a print copy of the particular book. But also you must have the correct edition.
For example, I have an 1869 copy of The Life and Epistles of St. Paul (2 Vols) by Conybeare and Howson. Unfortuately, the 1869 edition has slightly different pagination. This is not because its the abridged “People’s Edition,” but because there is a preface and introduction written by another person. Because of that whenever I search it in Logos, I have to either go back a couple pages or go forward a couple pages. Even still its a great resources and I’m very appreciative that Logos is willing to make even locked resources searchable. So in spite of the challenges, thanks Logos!