My large-format printer is a Canon. I have no idea whether HP's pro line is eligible for the program, but the HP printer I use with it is a bottom-end office AIO. They're explicitly targeting the consumer and SOHO markets in their promotional material for the program, so I'd be surprised if their pro stuff works with Instant Ink, instead of maybe with a similar program that's adjusted to work out better in the sort of context where a higher-end printer like that will see use.