DynamoDB is an Amazon key-value NoSQL database product. It has all the features you would expect for a cloud hosted database, but is designed as a cache and hence has very low response times. There is documentation at Fast NoSQL Key-Value Database – Amazon DynamoDB – Amazon Web Services and also Amazon DynamoDB - Wikipedia.

One thing to note is that the default "time-to-live" is 24 hours, this can be changed by adding an extra attribute to the entity, you can name this whatever you want but it needs to match the table config from when the table was created. It is worth noting that DynamoDB takes a "lazy delete" approach, in other words it could take up to 48 hours to delete something. It is important to read the documentation at Expiring Items By Using DynamoDB Time to Live (TTL) - Amazon DynamoDB on all of this.