No, you don't always have to. All faculties and Erasmus MC use the University Library Service Model, which means that a large number of publications are already added by the library.
You can add any missing publications yourself. Preferably by submitting the full-text file of your publication through the Quick-Submit option in Pure. The library will process the full-text and metadata (and supplement if necessary) as soon as possible.
More information can be obtained from your faculty key user and in the Pure manuals.
