> ## Documentation Index
> Fetch the complete documentation index at: https://www.helius.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Preprocessed Transactions FAQs

> Answers to common questions about the preprocessedSubscribe endpoint

## Using Preprocessed Transactions

> [accordion] Can you update preprocessed subscription filters live?
>
> No, the filter is fixed by the initial `preprocessedSubscribe`. To avoid a gap we recommend opening a second connection with the new filter, wait for its subscription acknowledgement, and then cut over your service to the new filter.

> [accordion] Is the preprocessedSubscribe concurrent subscription limit per API key or account?
>
> The 10 concurrent connection limit is enforced per API key. Each API key in a project gets its own 10-connection limit.

## Need More Help?

> [card] [Preprocessed Transactions](https://www.helius.dev/docs/preprocessed-transactions/overview.md)
>
> Learn about using Preprocessed Transactions

> [card] [preprocessedSubscribe API Reference](https://www.helius.dev/docs/preprocessed-transactions/preprocessed-subscribe.md)
>
> Learn about subscriptions, filters, and get examples


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