Used needles should be in a pen suitable container to be disposed, at the best in puncture-proof Wellion sharps container.
Unscrew the used pen needle after each injection from the pen - if you want you can use the outer protective cap. Catch them in the safe Wellion sharps container.
When the lid of the Wellion sharps container is sealed, it can not be reopened. The container will be disposed with the used pen needles.
This will protect uninformed persons of contact with used penneedles.