If you are an independent student the limit you can borrow on your Stafford loans is $57,500 and if you are a dependent student the limit is $31,000. These loans work a little like a credit card–any money you pay towards the principal of the loans becomes available to you again.
Many students who are only planning on getting their Diploma or AAS degree may never reach their limit; however, they have a greater chance of reaching their limit if they are going half time and/or withdraw or fail several classes. To be proactive you can ask the Financial Aid department where you are on your limits at any time–ultimately this is your future and your responsibility.
To help manage your loan limits the government has set up a website called the National Student Loan Data System (NSLDS) for schools and students to view your Stafford loans. This site can be accessed at www.nslds.ed.gov.