If you use WebFonts at a service that is usually script or css driven, but in Wix’s case we upload any OTF or TTF file. So I purchase those. I have actually been notified of a violation before, but share with them the multiple purchases. You may want to inquire with the service’s customer support and mention Wix. There are aware of the needs to utilize OTFs and can provide you a solution that should bring comfort to your concerns for use violations.