You can install Gift Voucher via the plugin store, or through Composer.
To install Gift Voucher, navigate to the Plugin Store section of your Craft control panel, search for
Gift Voucher, and click the Try button.
You can also add the package to your project using Composer.
composer require verbb/gift-voucher
You can try Gift Voucher in a development environment for as long as you like. Once your site goes live, you are required to purchase a license for the plugin.
For more information, see Craft's Commercial Plugin Licensing.
Available for Craft 3. Get it from the plugin store.