Pakistan is paid upfront, & it is covered under civilian aid all over the years. The government of Pakistan is in charge of the fuel, & all the civilian infrastructure of the country, & private Pakistani companies which provide for the trucks (also contracted by the US & Pakistan government). Which is why there is talk going on in the US about 'aid with strings attached & conditions met'.
The military aid was withheld from Pakistan, which was specifically used for maintaining military equipment/arms, military bases, other military services provided by the Pakistan Armed Forces.