There is a Spanish free book exclusive to subscribers:
https://es.logos.com/librogratuito/suscripcion
The book offered this month is:
https://www.logos.com/product/394334/el-proposito-divino-de-las-misiones
But when you get this book, it is not downloaded by Logos, and also it cannot be previewed on the website:
when clicking the "See Inside" button, it shows a message "Something went wrong. Try again."
Also it cannot be opened in web app:
https://app.logos.com/books/LLS%3ADIVENTRMISS-ES
shows a message "Sorry, we couldn't find that resource."