Can’t Type Messages Despite Paying For Pro Version

I bought the upgrade to allow me to type messages but since then every time I open DesktopChat for WhatsApp on my Mac I get asked to buy it again or restore my purchase. I have tried the restore my purchase a number of times and I still can’t write messages. Frustrating & annoying - can I get a refund!?

I Clarke about DesktopChat for Whatsapp