Absolutely. You will be able to get a free thirty day trial when you sign-up. No credit card information is required for this free trial. The trial will give you full feature access to the system, and allow you to maintain upto 100 subscribers in your account.
At any time during the free trial, you may upgrade your account to a higher subscriber capacity. After the thirty days trial has expired, you may upgrade your account to a higher subscriber capacity within seven days.