With the license change you have now 3 versions to choose from: Community, Professional and Enterprise Editions (more details here). The first Netbeans plugin for ZK 5 contained the enterprise version, resulting in a warning in the logfile the version will expire after 60 days. Since last week you can download the plugin that comes with the CE libraries.
Note: You need to install the other ZK5 plugin, de-activating is not enough. Download (link) and install as usual.
After installing the CE plugin your projects (created with the other version will throw a reference problem at you. You can’t resolve, you need to open the project properties and delete the previous library and import the new one. You need to verify if you used enterprise features that are not available in the community edition.