Our licensing model consists in three types of licenses and you'll have to decide which one best fits your needs:
Single use license - license for single DotNetNuke installation, which may host one or more subportals.
Additional license - it's the same as single use license, but it doesn't come with the installation package, so don't purchase it unless you purchased single use license before.
Multi use license - license for unlimited number of DNN installations that you(either an individual or entity) directly own and operate. Does not include the license to re-distribute to others.
The latest version of purchased products can be found in snowcovered my downloads page. You'll receive by email a serial number immediately after you order which can be used to activate purchased product.