earn one's keep vs pay the bills

earn one's keep

verb
  • To perform satisfactory physical labor or to provide other worthy services in return for remuneration, lodging, or other benefits; to support oneself financially. 

  • To be worthwhile. 

pay the bills

verb
  • To provide enough income to sustain one's lifestyle. 

How often have the words earn one's keep and pay the bills occurred in a corpus of books? (source: Google Ngram Viewer )