The phrase "eligible stays" refers to the types of stays or accommodation bookings that meet certain requirements or qualifications for a specific purpose. Full definition
As a gold member you are able to book free award nights 50 days in advance instead of 30, and earn an additional 10 % in points for eligible stays. (valuepenguin.com)
With Gold status, you can book free award nights 50 days in advance and earn 10 % bonus points on eligible stays! (upgradedpoints.com)
Gold is normally achieved after 10 eligible nights or 25 eligible stays in a calendar year. (austravelpoints.com)