• 株券かぶけん — stock certificate
• 金券きんけん — voucher / coupon
• 旅券りょけん — passport
• 馬券ばけん — betting ticket
• 優待券ゆうたいけん — discount coupon
• 食券しょっけん — meal ticket
• 入場券にゅうじょうけん — admission ticket
• 商品券しょうひんけん — gift certificate

券 represents a written or printed token that grants a right, value, or permission. It is commonly used for tickets, coupons, and certificates.

The focus is not the paper itself, but the benefit it represents—such as access in 入場券にゅうじょうけん or discounts in 優待券ゆうたいけん.