Do I have to pay the entire fee, irrespective of the day of the month when I activate the package?
Yes. However, if you activate the package after the 20th of the month, you may choose to activate it at the start of the following month and pay the fee on the 1st day of that month.
In this case, the monthly fee is blocked on your account and charged on the 1st day of the following month. If you change your mind before the fee is charged, you can cancel the package and the fee amount will be released.