IS THE AOC CREDIT GIVEN ONLY 4 TIMES IN A LIFE TIME OR DO I HAVE TO BE IN MY 4 YEARS OF COLLEGE

Four times in a student's  life time.  If you parent's claimed it, on your schooling, while you were their dependent, those time would count against your four. 

[EDIT] The AOC cannot be used for grad school, even if you (and your parents) used it less than 4 times while you were an undergrad.

Actually both rules apply.  You can only claim it for 4 years, and you can only claim it for your undergraduate degree (first 4 years of college or its equivalent.)  So for example, if you are a new US resident taking a graduate program, you can't claim the AOTC because you are past your first 4 years (undergraduate equivalent)  even though you never claimed it before.   Or, if you are taking 5 or 6 years to get your first degree, you can only claim it for 4 years.