The lift comes from the thrust of the engine and propeller when travelling vertically, in WW2 aircraft this is insufficient to continue so the plane slows rapidly and then stalls. However aircraft with bigger propellers and lower weight were introduced during WW2, they are called helicopters or sometimes rotary wing aircraft. Later jets could climb vertically, the lightning could for example, because it had massive thrust compared to its weight, however the maximum rate of climb was at an angle, at higher speed with the wings providing lift. An aircraft travelling at high speed in level flight then going vertical uses the wings to do so, this means an increase in AoA and drag, even with an engine providing 2,000BHP as thrust it slows rapidly and stops.Here is a silly question for you:
If an aircraft goes vertical when translating KE to Altitude, is it considered a Zoom Climb?
If so, Where is the lift when an aircraft is going vertical?