Just as companies are not static, neither is IP. It can pay dividends for companies to undertake a thorough review of their IP portfolio, as the company grows and changes, to determine what it is worth keeping in terms of intellectual property for further development and commercialisation, and what it might be better to sell or lease.
IP portfolios need to be reviewed on a regular basis to ensure that as organizations and legislation change, full protection remains in place.

Credit: https://minutehack.com/guides/some-surprisingly-interesting-facts-about-intellectual-property