GoDaddy really lived up to its bad reputation and recently changed their API rules. The rules are simple: either you own 10 (or 50) domains, you pay $20/month, or you don’t get the API. I personally didn’t get any communication, and this broke my DDNS setup. I am clearly not the only one judging from what I found online. A company this big gating an API behind such a steep price… So I will repeat what many people said before me (being right): don’t. use. GoDaddy.
I would suggest ddns.net if they hadn’t irrevocably eaten two of my domains already (when the client software doesn’t check in, the domain disappears from your account, but they don’t get marked as available so no other account can filch them)