Investigating Long Term Memory Persistence Across Different Platforms

I have been running some comparative tests regarding how various companion platforms handle context windows and long term memory retention over extended conversation periods. Specifically I am looking at how well core traits and past user shared details persist after several thousand tokens of interaction. Are newer updates genuinely improving persistent state recall or are they just utilizing better summarization tricks under the hood? When you all notice your companions bringing up something from weeks ago is it usually due to explicit database storage or just clever prompt injection by the developers? I am gathering data on consistency benchmarks and would love to hear your technical observations on whether memory degradation is getting better or worse lately.