Pubget is not a way to get around copyrights. In fact, Pubget cannot give a user access to any PDF or other material to which the user does not already have legal access. For example, if the user does not have access to a research article in the journal Nature (either through an individual subscription or through the user's institution), Pubget will not be able to give that user the PDF.
This is because technically, Pubget delivers only links to copyright-restricted content, not the content itself. If the user has access, then the link that Pubget delivers will lead to a page that displays content. But if the user lacks access, then the link will result in nothing (or more properly, in whatever free information exists about the content, such as a title, list of authors, perhaps an abstract, and a set of links). These links are not subject to copyright. In this way, Pubget respects all copyrights and legal restrictions on content and access.