You get profit/loss only when you close both positions. I don't know how much u paid for these position, but maximum value of this spread is possible when market closes above 4550 by expiry. If market remains above 4550, it will have value < 50.
So depending on your purchase price, you can calcualate the paper profit/loss.
If market goes below 4500, this position will start loosing value. Max loss will be at expiry when u still have open position and taken no action till then. Max that u will loose is the net premium that u have paid (i.e. Paid for 4500 call MINUS recieved for 4550 call).
This is called Bullish Call Spread position.. so please read about it to get more details.
Happy Trading.