Drip edge materials protect the edges of roof sheathing from water penetration due to consistent rains. The material is fixed at the edges and bent in a form that channels or redirects the water away from the edges protecting the roof wood from rotting and losing its robustness.
The drip edge material that extends past the sheathing edge supports the outermost edges of the shingles, enabling them to drip water while providing structural support so the shingles do not crack or split.
Though it might be expensive, but this onetime investment for you would be much better than changing the entire roof. Just try imagining the cost that would incur. So, installing the Drip-edge assembly before the onset of the monsoon season is a clever thing to do. It not only keeps your roof moisture free, but also provides a structural support.