card · starting from cardholder · unlocks 1 program (1 free)
If you already hold the Amex Corporate Green Card (US), you're one enrollment away from Hilton Honors Silver — no stay required, no spend threshold, just sign up and wait roughly 72 hours for it to post to your Hilton account.
Enrollment is restricted to Corporate Gold and Green cardmembers and the status isn't transferable to anyone else on the account. It's also not a set-and-forget perk: Hilton will deactivate the Silver status if you don't book and pay for at least one qualifying stay between the time you enroll and the end of the following calendar year, and then again every year after that. So the card gets you in the door for free, but keeping Silver active means putting at least one paid Hilton stay on the books annually.