title_body: If I only occasionally brew at home, should I keep instant or grounds (or something else)?
upvoted_answer: I've been that person - I kept ground coffee forever. The difference in taste between fresh and old ground coffee is enormous, but so is the difference between old grounds and instant. It's just a completely different beverage, so I would say if these are your two options, it's just a matter of personal taste (I would go for old grounds).
  
  If you're up for it, I would buy a small manual grinder and keep whole beans, it makes a world of a difference in taste and you can keep the beans for months without deterioration. Adds a bit of work to the process though, and depending on your coffee maker would require a grinder with different abilities (espresso would require much finer grinding degree than let's say a mokka express).