That said bitcoin's payment or remittance functions are what make the store of value function valuable. The more useful the payment functions are and are used the more valuable the store of value function becomes. Imagine bitcoin with no payment function but the same store of value function, yes the store of value function would work and remain fixed, but it wouldn't be valued very much.
The phrase "store of value" is almost completely useless because certain goldbugs have ruined it by treating it like some kind of intrinsic magical property.
It's best described as a behavior, or as an emergent property:
If the right conditions are met, a good medium of exchange can also behave as a store of value.