I think the key here is to take this as feedback for how you can optimize your product. e.g. You need to improve the user journey or add better copywriting to

I think the key here is to take this as feedback for how you can optimize your product. e.g. You need to improve the user journey or add better copywriting to your website to prepare them for the fact that this is a paid product. OR you need to offer a short free trial so they can test out the product and then pay for it. If you get many people wondering why it's not free, addressing this as product improvement feedback will lead to higher conversions and more revenue.