Minutes are not only a legal document for an organisation, they are also an historical record.
Depending on your legal requirements, you need to keep minutes for whatever the law requires but I stongly advise that organisations keep their minutes beyond that time.
One of the best ways is to scan them and keep them as a PDF stored on your organisation’s website. They can be passworded if necessary so only those authorised can see them, but it takes most (though not all) of the risk away from them being lost.
Minutes of meetings 50 years ago make fascinating reading!