Squaring off is not at LTP of option. It will be at CMP of Underlying minus Strike Price.
Eg.
You have bot RIL1000 strike call at 10 rs.
On expiry RIL is trading at 1049 and call is trading at 50.
Your option will be forcefully squared off at 1049-1000=49
and
49 x lot size will be credited into your account.
BUT
If RIL is trading at 999.50 and Call is trading at 3 rs. then too, nothing will be credited into your account at cmp for underlying is lesser than the strike price.
Hope this clears your confusion ....