To determine whether you need to continue paying $21.95 a month, you should first identify what this charge is for. If it is related to a Microsoft subscription, such as Microsoft 365, you may have options to manage or cancel your subscription depending on your needs.
If you are unsure about the service you are being charged for, it may be helpful to check your subscription details in the Microsoft 365 admin center or contact Microsoft support for clarification.
Regarding updating your credit card information, you can manage your payment methods through the Microsoft 365 admin center. If you need assistance, you can reach out to Microsoft support for help with your account and payment information.
References: