An API key will stop working in the following situations:
It was manually revoked by the key's owner;
The API access was turned off by a team administrator;
The password of the account it was linked to was changed;
For security reasons, changing your password will require you to re-authenticate on other sessions. This includes mobiles apps such as the D4H Equipment Management app, the Personnel & Training app and third parties, as well as other connected services like ConnectRocket.
If you need to (re) create an API key, see How do I obtain an API access key?