Put a person's name next to every software charge on your card statements
Export the last three months of card statements and write a person's name next to every software charge. Anything nobody claims gets looked into before its next renewal.
Most owners can say what a handful of their subscriptions do. The rest arrived one at a time. A trial someone started and forgot. Seats added for the busy season that keep billing in the slow one. Two tools doing the same job because two managers each picked one. A plan that renewed at a higher tier.
None of it is large on its own, which is why it survives. Twenty-three subscriptions averaging $90 a month is nearly $25,000 a year, and nobody ever approved that number as a whole.
The name matters more than the cancellation. A subscription with an owner gets checked when the team changes and when the renewal comes up. One without an owner renews forever. Check what an unclaimed one does before you cancel it, since some quietly run backups or keep a domain alive.
While you are in there, find each annual contract's cancel-by date and put it on the calendar. And where two tools both do scheduling or both do e-signatures, ask the people using them which one they would keep.
The first renewal this catches usually pays for the afternoon.