If I want to create a limit of 10 >requests per minute, I create a counter with a TTL of 1 minute and with an initial value of 10. Each time someone makes a request that affects this limit, the counter is decremented and the request is authorized as long as the value is > 0. When it is 0, the request is considered to be limited and is rejected until the key expires. When the key has expired and the next request arrives, the same TTL and initial value is recreated.