It will help your executor or personal representative to sort out your financial affairs when you die if you keep a record of any gifts you make and note on that record which exemption you’ve used.
It’s also a good idea to keep a record of your after-tax income if you make regular gifts out of income as part of your normal expenditure. This will show that the gifts are regular and that you have enough income to cover them and your usual day-to-day expenditure without having to draw on your capital.