How long do round trip tickets last?

Related questions

1. Is round trip cheaper than one way?
2. Does Korean Air offer free stopover?
3. Why are flights with stops more expensive?
4. Why are some flights cheaper than others?
5. Are flight tickets cheaper at the airport?
6. Is it cheaper to book hotels directly?
7. Is it cheaper to book return flights?
8. What is the longest layover allowed?
9. How does a Disney travel agent get paid?
10. Do hotels drop prices last minute?

Tags

1. #airlines
2. #amount
3. #class
4. #depending
5. #month
6. #rates
7. #paying
8. #maximum
9. #often
10. #cheapest
11. #round
12. #return
13. #duration
14. #tickets
15. #offer
16. #change
17. #difference
18. #stays
19. #reasonably