Do unique promotional codes ever expire?

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Nowadays, I've been seeing promotions that involve two types of codes; a global code (ie. HAPPY-2015
)1 and a unique code (ie. 1234-5678-9012
)2.
I know that these global codes expire as the expiry date is always stated with their post.
However, there isn't any information about unique ones.
1 These codes can be used once per account in the given timeframe.
2 These codes can only be used once on one account.
I've bought a code through Humble Bundle (Bundle ended, page is out-of-date) and received another as part of the Curse promotions.
I haven't used either of them and I was wondering: Do they ever expire?
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Do promo codes only work once?
On average, coupon/promo codes work only about a third of the time, says Walt Roloson, co-founder of Wikibuy (owned by Capital One), a popular online shopping browser extension that finds and applies coupon codes during checkout.Can promo codes be used more than once?
Some promo codes can be used on multiple orders, but many codes are only valid for one purchase. To see if your code can be used on multiple orders, review the Terms & Conditions associated with your code by tapping the details link on the promo banner in the app.What is unique promo code?
Unique Coupons A Unique Coupon, on the other hand is a coupon code that is assigned to one and only one person when they sign up. As an example, if customer A and customer B sign up each will receive their own code which would not be transferable between them even though their discount is the same.Promo-code that never expires!!!! (actually works)
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