Memory

• https://docs.langchain.com/oss/python/concepts/memory
• https://github.com/NirDiamant/Agent_Memory_Techniques
• The implementation of several types of memory is done at different steps in agent loop

	Short Term Memory	Long Term Memory
Psychology	lasts for 15-30 seconds	lasts for more than 30 seconds
LLM	current session	shared across multiple sessions

Short Term Memory

• aka Thread scoped memory or working memory
• tracks ongoing conversation by maintaining message history
• LangGraph uses State and Checkpointer to achieve this

Long Term Memory

• user specific or application data
• shared across conversational threads
• can be implemented with Vector Stores
• Based on Human Psychology LTM is classified further
• Types
  • Semantic Memory
  • Episodic Memory
  • Procedural Memory
• LTM implementation depends on
  • what kind of memory?
  • when do you want to update the memories?
    • in the hot path
    • background async

LTM Type	What is Stored	Psychology Example	Agent Example
Semantic	Facts	Things I learned in school	Facts about a user
Episodic	Experiences	Things I did	Past agent actions
Procedural	Instructions/ Rules	Instincts or motor skills	Agent system prompt

Semantic Memory

• can be implemented by semantic search by vector DB
• fact based, when and how does not matter
• examples
  • user preferences
  • domain knowledge

Episodic Memory

• can be implemented by key-value structured DB
• save memories as episodes indexed by time and topic
• what happened when type questions
• examples
  • multi-sessions to remember previous sessions
  • coaching agents to track progress over time

Procedural Memory

• handled by fine tuning and prompts
• capture “how-to” knowledge
• examples
  • reusable skills
  • multi-steps tasks like data pipelines or API integrations

Cognitive Architectures

Memory Consolidation

• Merge, deduplicate, and strengthen memories

Memory Compaction

• Compress stored memories with summaries, entity extraction, or distillation

Memory Decay

• Give more weight to recent memories compared to old memories
• Versioning of memories can help
• Forget on purpose

Tools

• Mem0
• Zep

Production

• Caching frequently used memories
• TTL policies to remove stale memories
• Horizontal sharding
• Backup and Recovery
• GDPR and PII
• Observability
• Cost management