Credit Where It’s Due

My checkbook
is on the Bank of Time.
My checks will be honored
for any amount
not to exceed my lifespan.
I am guarantor and collateral.
I don’t have to promise,
only fulfill.
I will give you this
which cost 500 hours,
or that, only two.
It’s mine to give, mine only,
and if you don’t like it,
it will cost but seconds to refuse,
you need not return it.