Let me try to answer you here for the benefit for other readers...
First of all... congratz!!! Nemo breeding non-stop in captivity is a very good sign
1) Yes, Roti-Feastâ„¢ has a lifespan
2) Yes, it is better to buy from a fresh source (just like we buy fresh produce from market)... that's why AM only bring in limited amount every month... they don't keep stock for long... that's why sometimes reefers get disappointed if the demand gets higher than supply... I heard US side demand too high... so they can only send limited bottles to our tiny little island.
3) The date stated on the bottle is based on no-refrigeration... so if you are to keep it in the fridge all the time... it will prolong the expiry date by 3 months.
4) I'm sure your baby Nemos will enjoy Roti-Feastâ„¢ very much... so what are you planning to do once they grow up? Perhaps you wanna try selling them
Was at AM today... saw a reefer bought a bottle, I think they still have stock for this month