If you send a file in a single Perplexity thread and find out that it can no longer be used as a context after a few days, it's usually not a mysterious loss of the file, but rather a mix of a thread attachment and a persistent knowledge base file. Perplexity's current help center is clear: files uploaded to Threads are deleted after 7 days; However, files placed in Spaces, your personal library, or your organization's library will remain until you actively delete them.
So they are all "uploading files", and the lifecycle behind Thread and Space is completely different. The former is more like a one-time conversation context and is suitable for ad-hoc Q&A; The latter is like a continuous layer of knowledge, suitable for long-term reference.
This is why many team users feel that "the file is still there, why is the follow-up answer suddenly no longer quoted". The problem is not necessarily that the model forgets, but that the location you upload has only a short-term retention strategy.
If you want to avoid this situation, the safest thing to do is:
1. Temporary analysis and one-time Q&A, just upload it with Thread.
2. If you want to keep the data for a long time, put it in Space, My Files, or organize a file library.
3. When you encounter a task that you want to ask questions in a few days, don't just leave the file in the thread.
Another misunderstanding is that Thread itself may not disappear immediately, but the file content may no longer be used by subsequent questions. In other words, you can still see the historical answers, which does not mean that the background still retains the context of the document that can be continued to read.
So if your goal is to follow up on the same set of data for a long time, don't think of Thread as a permanent repository. Perplexity's file retention policies for different ingress vary greatly, and if you place it in the right place, the subsequent experience will be stable.
