earn one's keep vs subsist

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. 

subsist

verb
  • To survive on a minimum of resources. 

  • To have ontological reality; to exist. 

  • To retain a certain state; to continue. 

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