The main reason why the American presidents 'memorials were so expensive was that their memorials were often regarded as books with important historical value, which played a vital role in understanding American politics, society, and culture. In addition, the royalties for the American president's recollections would be sponsored by the publishing company and readers. These sponsorships would usually translate into higher royalties. The American president's memorial would also be supported by the government. The U.S. government usually provided funds for the compilation or revision of history books to ensure the quality and value of these books. In the end, the amount of remuneration would also depend on the popularity and quality of the book. If the book was widely accepted and welcomed by readers, the royalties would usually be higher.