Long term memory, e.g., a lot of data, you will be better off using existing data systems if it's already there. Or use modern search engines like Elasticsearch, Opensearch, Weaviate, Vespa, etc.
Short term memory, e.g., something that's short term, in memory, for sessions, e.g., baybAGI/autoGPT type of stuff, duckDB, ChromaDB (basically duckdb + hnswlib), Redis, or just directly use an Numpy array.