PRIME during cycling - how long does it protect from ammonia

[Bubble_B0y]

from seachem

Prime™ converts ammonia into a safe, non-toxic form that is readily removed by the tank’s biofilter. Prime™ may be used during tank cycling to alleviate ammonia/nitrite toxicity.

Use 1 capful (5 mL) for each 200 L (50 gallons*) of new water.
This dose removes approximately 0.6 mg/L ammonia

according to the label - PRIME can be used during cycling and detoxifies ammonia, so the fish are protected.

My question is:
how long are the fish protected?
will the prime be eventually used up?
do you have to keep adding prime to maintain this protection?

 

[exodus]

unless you already have fish in the tank, I'd wait until its cycled naturally.. adding chemicals should be a last resort.