for keeps vs once and for all

for keeps

prep
  • With an agreement or intention to retain what one gains or receives. 

  • Permanently, so that one can keep something indefinitely. 

  • With a strong competitive resolve to win or succeed, as in sports or business. 

once and for all

adv
  • Finally, permanently, conclusively. 

How often have the words for keeps and once and for all occurred in a corpus of books? (source: Google Ngram Viewer )