Members, Sr. Members, Legendary Members who will have so many sMerits to share. If they have not sent yet, they can send that without allowing it to decay.
This has been done for a long time, by other members, they do not keep sMerit, everything has been given to other members, who are entitled to receive it.
Don't worry, sMerit won't rot.
Most generous merit senders, all timeMost generous recent merit sendersbut there is no where mentioned about the date or time period when sMerits will be decayed or destroyed.
Indeed:
Merit sources
There are 131 merit sources with a total merit generation of up to 21045 sMerit per 30 days