Every credit in a member's points balance is written as its own entry, with the activity that created it and the date it was credited.
That matters for two reasons. The first is that a member can see why their balance is what it is, rather than being shown a total and asked to trust it. The second is what happens when something is undone: a referral that is later cancelled or refunded does not have its points deleted. A compensating entry is written instead, so the history still shows what happened and when.
It also means a balance can be verified. When an application is assessed, the points behind it can be traced back through the entries that built them.