Summarize:

Though every student who qualifies "will receive their grant in full," there are a few small exceptions. The government likes to know you're going to stick to your word -- if you're failing out of college, they may deem you a lost cause and cease aid. What's more, the better your grades, the more other grants you may receive, so it's just good common sense. If you receive a criminal conviction while you're a student, your eligibility may change. Don't assume you can't get funds, but do know that it may be more difficult. It all depends on your specific situation. You are only eligible for Pell grants for 12 semesters, or six years. They do not have to be consecutive, but that is the limit. You will receive a notification if you are nearing the checkpoint. In order to receive loans and grants, you have to file the FAFSA every year. This is because your tax information may change and has to be accounted for. Though you'll use the same pin, you still have to file. Act quickly. Though the Pell grant is not awarded on a first come, first served basis, it is best to do it as quickly as possible. The earlier you apply, the more other grants you may receive.
Keep your grades up and record clean. Finish in six years. File every year.