How to know who created a Nintex Form in my list?

Hi John Edward Paredes‌

Open your site in SharePoint designer 2013. Go to All Files > Nintex Form XML. Check modified column. See if this helps.

hi Kapil Joshi‌,

Thank you for your response. Can I do this in SharePoint Online? I Can't find it in SPO.

Yes, I am using SPO. If you cannot find it, that may most probably indicate that it has not been activated.