do I still have to pay the fee, if I won’t use it.
Yes. In order to keep your number, you will still have to pay for it even if you don’t use it. If you cancel service without porting the number, you will lose it. I am not sure what phone you have, but if you have a legacy device (Moto X1 and X2, Moto G1 and G3, or Moto E1 and E2) you can switch to the $5 WiFi only plan for those 2 months. Another option (whether you are on a legacy device or 3.0 device) would be to port the number to a number holding service (like Number Barn) and pay them to hold it. For two months, it may be cheaper to go with Number Barn, but the difference is only a few dollars and may not be worth all the hastle. Of course, if you don’t mind losing your number, you can just cancel service and reactivate whith a new number when you get back. Hope that helps!