cease and desist vs let up

cease and desist

verb
  • To stop and not resume an action. 

noun
  • A demand that one stop and not resume continuing a certain behavior, such as copyright infringement, trademark infringement, slander, or libel. 

let up

verb
  • To cease or stop (doing something intense). 

  • To cease or stop. 

How often have the words cease and desist and let up occurred in a corpus of books? (source: Google Ngram Viewer )