Rolling

VikramAdi So like this?

Cumulative Measure = 
  VAR __Date = MAX('Date'[Date])
  VAR __Table = SUMMARIZE(FILTER(ALL('Dates'),[Date]<=__Date),[Date],"__30Avg",[Rolling 30 Days Average])
  VAR __Result = SUMX(__Table,[__30Avg])
RETURN
  __Result