Spot premium for opening long option token positions (buying long options):
$1 - (strikePrice * underlyingReserve / shortReserve)$
Spot premium for closing long option token positions (selling long options)
$1 - (underlyingReserve / (shortReserve * strikePrice))$
Where underlyingReserve and shortReserve correspond to the Uniswap Pair for the option.