One Vizlib user license allows an individual to use all Vizlib Extensions in the whole Qlik Sense environment based on their UserID. This is the same whether they are an app developer, app user or end user. A Vizlib license will account for all use cases for that one named user and is the same as an assigned Qlik Sense Token.
This means that in different environments, there will be a user license allocation required for each environment, for example, in 2 environments, 2 allocations will be used
UserIDs in the Qlik Sense Server Management console: