A Federal Pell Grant, unlike a loan, does not have to be repaid.  Federal Pell Grants are awarded only to undergraduate students, who have not earned a bachelor's or professional degree.  

A FAFSA application must be submitted. To determine if you're eligible financially, the U.S. Department of Education uses a standard formula, established by Congress, to evaluate the information you report when you apply. The formula produces an Expected Family Contribution (EFC) number. Your Student Aid Report (SAR) contains this number and will tell you if you're eligible.

The enrollment status of the student i.e. full-time, three-quarter time or half-time will have a proportional effect on the amount of money the student will receive. Student awards will be adjusted each term, to match their enrollment status, as of the term census day, resulting in a lower amount, to match the eligible financial aid credits for the term.  Repeat courses and courses, not in the student's degree plan may, cause the student to be eligible for a lower award for the term.