Help To Determine Lease End Date.

[Simple99]

My starting date is 8/26/20. The agent is telling me the end date is 2/28/21 and us making me pay more for the extra days. My question is if the lease states a 6 months, my end date should be 2/26/21 correct ? I am planning on returning the keys on 26. What should I do in this matter.