E-register Now on WordPress Website

Hi There,

I am not yet using a wordpress website however I am proposing that the organization I work for begins to use it. The organization is an association and has members. Right now the members pay their annual fees by telephone or money order. The organization pays for an online software called e-register now and would like to use it to allow members to renew and pay for their membership online. Can I use this software with wordpress or do I have to use an e-commerce plugin that is supported by wordpress? Is their anyway that I can use the e-register now software that they already use?