Join Date: Oct 2005
Location: Ponte Vedra Beach, FL
Programs: DL PM, HH Diamond, Fairmont Prem, SPG Gold, Priority Club Plat/IC Amb, AmEx Plat
Posts: 10,839
Other than LUT and paying with your DL AmEx, I know of no restrictions on the certificate. The fact that it is online makes it super easy to use, I went looking yesterday for flights and DL.com gave me eligible flights for the day I searched.