for keeps vs forever

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. 

forever

adv
  • We had to wait forever to get inside. 

  • For all time, for all eternity; for a lifetime; for an infinite amount of time. 

  • For a very long time, a seeming eternity. 

  • Constantly or frequently. 

noun
  • An extremely long time. 

  • A mythical time in the infinite future that will never come. 

adj
  • Permanent, lasting; constant, perpetual. 

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