Shown above are portions of an advertisement for The Science Fiction Book Club that was bound inside a paperback edition of No Time Like Tomorrow, a collection of short stories by Brian Aldiss.1
These types of heavier stock advertisements (this one had a perforated edge) used to be quite common within paperbacks, especially in the 1970s. (Paul Collins wrote about the history of the practice, and the proliferation of cigarette ads, in a 2007 essay in The New York Times.)
Internet Speculative Fiction Database cannot determine a publication date for this specific edition. But there was another edition with this same cover published in 1971, so that year is a very fair guess.
The Science Fiction Book Club was founded in 1953 and is still around today (with a much different membership model, of course). Here's just a little bit about the club's extensive history, from the Internet Speculative Fiction Database:
"Doubleday created the Science Fiction Book Club in 1953, offering one selection per month, with the first book appearing in March. This practice continued until July 1969, when the club began offering a second selection. Both books were sent to members who chose to receive them (or forgot to mail back the selection card!) Around this time additional selections were offered in seasonal announcements (Winter, Spring, etc.) This gave members a choice of up to 32 new books each year, while occasionally making available 'alternate selectons' and cross-over selections from other Doubleday book clubs. These alternate selections were not automatically sent to club members. The practice of offering alternate selections gradually grew over the decades, from one or two in the 1970s, to a dozen or more in the late 2000s.In this advertisement from about 45 years ago, the club offered three books for just $1 (plus shipping and handling) as an enticement for new members. After that members had to purchase just four books (at $1.49 apiece, plus shipping) during the subsequent 12 months in order to satisfy their membership requirements. That doesn't seem too bad, depending what the shipping costs were. You would pay $7 for 7 books, if my math is correct. That's the equivalent of about $41 (for seven new books) today — about $6 per book.
"In the beginning the selections were mostly reprints of books originally published by Doubleday's trade division, and were of comparable quality. As the years went by, more publishers' books were made available as the monthly selection. These printings had to be reset to conform to Doubleday's printing presses, and were mostly of cheaper quality."
Some of the books that were available via this new-member offer were The Science Fiction Hall of Fame, edited by Robert Silverberg; The Foundation Trilogy by Isaac Asimov; 2001: A Space Odyssey by Arthur C. Clark; Stranger in a Strange Land by Robert C. Heinlein; and The Left Hand of Darkness by Ursula K. LeGuin.
The advertising copy states: "You'll be offered other equally exciting books — to build your own hall of fame ... you own science fiction library — at a fraction of their regular cost. That's what membership in The Science Fiction Book Club is all about."
1. Sarah saw this and said, "Ooh, neat. ... It's an ephemera about books, Dad. What could go wrong?"