If you're a Joomla extension developer trying to sell licensed software with proper "one-click Update" support — the same experience Akeeba's own Admin Tools Pro and Akeeba Backup Pro give you — you've probably discovered there is almost no documentation for this anywhere. Stack Overflow is silent. Akeeba Release System (ARS) has no free support and isn't listed as a supported product on Akeeba's own support page. The one useful thread we found was a decade-old support ticket. Everything else, we had to reconstruct by reading Joomla's own core source.

This is the write-up we wish had existed before we started. It covers the complete chain: a Joomla package-type extension manifest with proper Download Key support, the update stream on Akeeba Release System, and the storefront (in our case J2Commerce) that actually issues and gates the license key. Every section below corresponds to a real failure we hit, in the order we hit it, with the root cause and the fix.