Open the last two months of card and bank statements. List recurring services with the amount, billing frequency, next renewal date, and which account pays. Check email receipts for annual plans that did not show up in that window.
For each service, write down when you last used it and who uses it. Mark it keep, review, or cancel. If you cancel, save the confirmation and check the next statement for another charge.
The GGC Studios Household Subscription Audit includes printable pages for the inventory, usage review, and cancellation record: https://payhip.com/b/oBKgH