Scores are valid for five years (at most institutions) from the date the test taker sits for the exam until the date of matriculation (i.e. acceptance, not until the date of application).
However it is advised to the candidates that the scores should be more recent, i.e., not more than 2 years older.
All your scores will be written in the report as long as they are valid ( less than 5 years).Thus, if you take the GRE for 10 times in 3 years ( not more than 5 times in a year and one time in a month) all your scores will be reported.
SCORE CANCELLATION :-
A candidate can cancel his/her GRE score before he sees his test score.
However, cancelling score is not recommended because of the following reasons:
Usually you think you did worse, but it may not be the case.
And even if you don’t cancel, you can always reappear for the exam.
The only cases in which we would recommend canceling are those in which you had an extreme circumstance which caused a very poor performance (illness, bad testing environment, etc.).
However, once you request an unofficial score report (immediately after the test), you no longer have the option of cancelling your scores.
If you even cancel your score, then they will indicate that this person on this date and in this place (Place of exam- code of it) took the GRE and cancelled his/her exam.
However if you do cancel your score, of course you won’t be able to see your score, but the record of that exam will not appear in the report as well.