When the free plan is enough
Free covers ordinary files. Pro is for the day the cap, not the tool, is the problem.
The free tools are not a demo with the buttons disabled. You can merge, split, compress, and convert without an account, inside a size and a daily count that keep one shared server usable.
You will feel the edge when a scan is over the guest limit, when you need twenty files instead of one, or when you are back tomorrow and the counter has not reset yet. That is the Pro conversation: 100 MB files, 500 pages, batch runs, no daily cap, a shorter wait when the queue is busy, history for the hour the file still exists, and an API key for the same processors.
Pro does not add a secret high-quality converter in the cloud. Advanced compression means the same Ghostscript presets on larger files. Word conversion stays a text extraction. The upgrade is capacity and quiet, not a different product underneath.
If you are deciding for a team, start on Free for a week. Upgrade when the limit message is the thing you remember, not the tool. The pricing page is the whole comparison, including Bitcoin if you would rather not use a card.