Hi Aratrika,
When you choose to send your Score results to a School, what you're really doing is granting that School the access to view your Official Score Report. Since a GMAT Score is 'valid' for 5 years, then that's how long each School will be able to access the Official Score result. The School won't actually look at the Report until you apply though (and only if the School is considering inviting you to attend) since there's no reason to pour over thousands of Official Scores until/unless it's necessary.
If you take the GMAT at a Test Center, then you can select up to 5 Schools to receive that access. If you want to apply to MORE than those 5 Schools (or perhaps different Schools than the ones you selected on Test Day), then you have to pay an additional fee per School to grant those Schools that access.
GMAT assassins aren't born, they're made,
Rich