Lambert Academic Publishing is a scam. LAP is a company based in Mauritius and Eastern Europe that spams scholars who have published theses offering to republish them as books.
The naive and gullible agree, and after zero editing or reviewing (changes are even charged for!) LAP create a front cover using stock art and place the "book" online (on their own site and sister sites, and on Amazon) for sale at high prices with no indication that this work is an unedited thesis. The only sales will be to unwary libraries or hobbyists, but the author never sees a penny of those sales.
Then begins the next stage of the scam - the hard sell. Scholars are drawn in by the promise of royalties but these are a mirage. In reality, LAP presses authors to buy expensive copies of their own book! Not only do these authors risk being out-of-pocket, but they also risk damaging their reputation by publishing with LAP.
Matt Hodgkinson, Head of Research Integrity at Hindawi Publishing Corporation (2016-present)