durably vs for keeps

durably

adv
  • In a durable manner. 

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 durably and for keeps occurred in a corpus of books? (source: Google Ngram Viewer )