The key supplied with the ZEMAX software is worth the full purchase price of the software. If the key is lost or  stolen, it will not be replaced without payment of the full purchase price.

Insure the key as you would any other  business or personal asset of comparable value, then file a claim with your insurance company if the key is lost or stolen.

Defective keys, or keys that become inoperable, will be replaced  at no charge if the key has a current support contract. Defective keys must be returned before a replacement key will be provided. See this article for details.