Slack Forgets Everything Older Than 90 Days Unless You Pay
Slack’s free plan does not archive your conversations, it expires them. Messages and files older than 90 days become inaccessible, and the practical effect is that a team’s institutional memory has a rolling shelf life. The vendor’s own help documentation on free-plan limitations is straightforward about this, and about the fact that conversation summaries, huddle notes and other AI capabilities disappear entirely if a workspace downgrades. For any organisation using Slack as its primary discussion channel, that is the decisive constraint.
Slack plan facts, USD, checked August 2026
- Free retains 90 days of message history on a rolling basis
- Pro is $8.75 per user monthly or $7.25 billed annually
- Business+ is $18 per user monthly or $15 billed annually
- Enterprise+ is quote-only and adds enterprise search
- Agentic Slackbot is a Business+ and Enterprise+ capability
Ninety days, then it is gone
The limit applies to messages and to files, and it is a rolling window rather than a cap on total volume. A decision made four months ago in a channel is not merely hard to find, it is unreachable. Teams that have used Slack for years on the free plan are frequently unaware of how much has already been lost.
There is a widely discussed argument, made forcefully by competitors and by open-source advocates, that this converts a communication tool into a subscription for access to your own conversations. That framing is polemical but the mechanic is real, and it is the single most effective conversion lever Slack operates. Anyone treating a free workspace as a permanent record should export regularly or plan to pay.
Pro at $7.25 and what the money buys
Pro removes the history limit and unlocks unlimited integrations, group huddles with screen sharing, and the basic AI capabilities including conversation summaries, search answers, daily recaps and file summaries. Annual billing brings the rate to $7.25 per user from $8.75 monthly.
For most small and medium teams this is the correct plan, and the value is almost entirely in the history. The AI features at this level are convenience rather than transformation: a summary of a busy channel is useful on a Monday morning and is not a reason to choose Slack over an alternative. The integration catalogue, which is the deepest in the category, is the more durable argument.
The upgrade from free to Pro is also the point at which a workspace stops losing data, not the point at which it recovers it. Messages that expired under the 90-day window on a free plan do not return when payment begins, because they were not retained. Teams that have been running free for a year and expect an upgrade to restore their archive are consistently surprised by this, and it is the strongest practical argument for paying earlier rather than later.
Business+ at $15 and the agent gap
The jump to Business+ roughly doubles the seat cost, to $18 monthly or $15 annually, and the differentiators are now substantially AI. Slack’s positioning describes Slackbot at this level as a personal AI agent rather than the scripted responder it used to be, and Business+ adds AI language translation and writing assistance inside canvases.
The security and compliance content matters at least as much. SAML single sign-on, user provisioning, data exports for all messages and higher uptime guarantees are the reasons organisations of any regulated size end up here regardless of the AI. Presenting the tier primarily through its AI features rather than its compliance features is a marketing choice that obscures the actual buying rationale.
The features that hold teams in place
Slack’s stickiness is not primarily a function of its plan structure. It comes from a set of features that quietly become part of how a team operates, and each one raises the cost of leaving a little further.
- Huddles, which have quietly replaced scheduled calls for many teams and are hard to leave behind
- Canvases, which embed structured documents directly in channel context
- Workflow Builder, allowing non-technical staff to automate routine requests
- The connector catalogue, which remains the widest of any team messaging platform
- Slack Connect channels with external organisations, which create switching costs beyond your own walls
The notification economy
The most substantive criticism of Slack is not commercial. It is that the product’s defaults optimise for responsiveness at the expense of concentration, and that organisations adopt it without adopting any norms about how it should be used. Channel proliferation, expectations of immediate reply, and a stream that never has an end state are cultural problems the software actively encourages.
Slack has added scheduled sending, focus tools and granular notification controls, and they help those who configure them. The defaults do not, and most people never change the defaults. Any organisation rolling Slack out should write the norms first, because retrofitting them onto an established habit is considerably harder.
Export, retention and getting the record out
Standard exports on the lower tiers cover public channel content. Comprehensive exports that include private channels and direct messages are restricted to higher plans and are typically subject to a compliance review process, which is appropriate but slow.
Custom retention policies are similarly a paid capability, and they matter in both directions: some organisations must retain everything for regulatory reasons, and others must delete on a schedule for exactly the same reason. Neither is achievable on the free plan, where the 90-day expiry is imposed rather than chosen.
The practical advice is to decide your retention requirement before deployment rather than after an incident. Slack can satisfy most policies at the right tier, but the tier is determined by the policy, and discovering that relationship during a legal hold is an expensive way to learn it.
Sources: Slack pricing · Slack help, feature limitations on the free version · Zulip blog, who owns your Slack history · Cloudficient, Slack data retention policies
