If you purchased Smashkey from Gumroad, you will be presented with a download page and a license key. We will e-mail any updates for that version to you including a link to download any updates, or fixes.
You can enter the key in Help > Enter License
Your license is valid for a single version. All minor version updates are included as part of this key. When a new major version is released, a new key can be purchased for that version.
Older versions will not be disabled but but may not receive any further updates.