Piano won't stay in tune

[Hechler, Duaine & Laura]

Newbie question.

I tuned a piano for a lady and she told me that the guy before me told her that the piano won't stay in tune.

I was looking through the Schaff catalog and saw some stuff called "Pin
Tite".

Is that what I need to buy ?

If so, do I put a drop at each pin next to the pin block ?

Thanks,
Duaine