You can create unlimited, inherited secured API keys as stated here: https://www.algolia.com/doc/guides/security/api-keys/#number-of-keys
These secured API keys are virtual keys which are created and inherited from predefined API keys.
The maximum limit of predefined API keys is 5,000 but please note that you should keep your count below this limit.
As stated in our docs:
To avoid unmanageability and unauthorized use, create as many keys as you need, but no more. Make sure you revoke keys when you no longer need them.