for ever and ever vs for keeps

for ever and ever

adv
  • Forever. 

  • Eternally; timelessly; with no beginning and no end. 

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. 

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