There's no point in this.

Said differently, this nullifies the use of promo codes.

With Amazon, there are near zero analytics.

You're only hope of crude tracking is to keep your promo codes private, only provided in specific email or direct mail copy, to have some sloppy guess about who's buying your product.

Best to also expire these quickly, because if you leave running for years, someone will pass this along to their list, which passes it along to other lists.

Long term promo codes dilute data to an unusable point.

Tip: Also, include some device on your product to drive people back to your site.

Since you provide no information, no clue as to how to structure this device.

Example: Say you're selling bagged Maca on Amazon. One each package you'll include something like...

Email recipes@super-duper-great-maca.com for a free recipe book on 101 Maca recipes + energy boosting hacks... in 101 easy to implement email messages.

Some device to collect purchaser information.