Asset store copyright

hello I want to upload a package to asset store, should I get the copyright of this package myself or does unity do this?

Afaik you yield your copyright to everyone who downloads/buys your stuff from the Asset store unless not stated otherwise - there is a default eula/license agreement for the asset store. If you want to have a different approach you might have to discuss that with Unity.

Read this if not done already:
FAQ Asset Store Eula