Yes, a credit card is required at the time of purchase. This will allow for seamless activation of your membership after the initial 3-month period.
When you enter your credit card details during the setup, you are securing continued access to premium features at the end of the 3-month period.
After this period, the $4.99 monthly fee will automatically be charged to your card unless you decide to cancel your membership. This ensures there is no interruption in service.