Not exactly sure what you are asking- crustacean sperm are non-motile, so they can often remain viable for a long time after being deposited

Dear Dr. Maheswarudu,

In penaeid shrimps when copulation occur the sperm is stored in seminal vesicle (sperm sack) of female which remains viable condition for few days.  Therefore,  until shed off exoskeleton during next moult the sperm remains alive. I hope this may clear your doubt.  

Also, maturation and capacitation of the sperm occur in the thelycum of the female. There is no exact research yet, but there could be some trigger within the thelycum of the female that prompts the sperm to proceed to maturation and capacitation. If the sperm sac remained within the male (unused because of no copulation), it would have been otherwise absorbed by the time the male shrimp molted.

Like was said before, the sperm remains viable for a long time. A single mating encounter can fertilize several spawning events of the female

Asif, remember that Penaeus vannamei is a open thelycum species

 Dear Shikder Saiful Islam,

Decreasing viability of sperm after first spawning of the particular moult cycle is encountered in induced breeding by eye stalk ablation, which is due to decreasing egg quality but not the sperm quality. During Induced breeding without eye stalk ablation this drawback is not encountered. Please go through the following two papers, where induced breeding is stimulated with environment and by feeding littoral oligochaete, Pontodrilus bermudensis from which  shrimp maturation stimulator was identified (attached). Thank you for your active participation.

Article Littoral Oligochaete Pontodrilus bermudensis Beddard: A pote...

Article Repetitive maturation and spawning of the green tiger prawn ...

Article Repetitive spawning of Penaeus indicus without eyestalk abla...

Dear Abdulla-Al-Asif,

In open thelycum penaeid shrimp spermatophore is attached/deposited to female just few hours before spawning   performance by female where the question of existing live condition of sperm for number of days (one moult cycle,about 20 -25 days) will not arise. Thank you for participation.