The Workflow Power Pack downloadable from this page covers all different license types, SharePoint Editions (including SharePoint 2010) and available languages.
If you are downloading the software for evaluation purposes then a license is not required. Without a valid license the software will be fully functional with the exception of a small message in the user interface and the workflow log.
If you have purchased a license then you can download the license key from your order details page. After installing the license the evaluation messages will disappear, there is no need to reinstall the software.
Information about how we license our products is available here. Detailed pricing and an overview of available licenses for this product can be found here.
The current version of the software is 22.214.171.124 (Release notes).