Your formula has a couple of issues, including overloading of t. I assume you meant the following (in LaTeX notation):
\sum_j j x_{ijt} = \sum_{s=\max(1,t-8)}^t y_{is} + \sum_{s=\max(1,t-16)}^t z_{is} + \sum_{s=\max(1,t-24)}^t w_{is} \forall i,t
If so, you can write this constraint in PROC OPTMODEL as follows:
con Mycon {i in ISET, t in TSET}:
sum {j in JSET} j * x[i,j,t] = sum {s in max(1,t-8)..t} y[i,s] + sum {s in max(1,t-16)..t} z[i,s] + sum {s in max(1,t-24)..t} w[i,s];