Zoho Creator no longer allowing PayPal transactions without upgrade

I have been successfully making actual, real transactions to PayPal through a payment form I created in Zoho Creator. I now receive the message shown in the screen shot.

What would cause this to stop working? Everything worked and than suddenly stopped. As much i as I like Zoho products, I sometimes think I made the wrong decision getting my organization too much into Zoho. Time to look elsewhere?

I'm guessing the free plan does not include the payment module and I was unknowingly using a premium feature. My organization simply cannot afford the Zoho Creator prices. As much as I like Zoho time to move on. Sites is nice at $39 per year and we will continue to use Sites, but I will go elsewhere for advanced payment features. My organization will only use advance features limited times per year and I cannot see paying Zoho Creator prices for limited use of advanced features.