PowerQuery - max date by product

Hi mb0307 

Have a try

let
  Source = Table.FromRows(
    Json.Document(
      Binary.Decompress(
        Binary.FromText(
          "i45WMlTSUTIw1Dew1DcyMDJUitWBChlhChljCpmgCBkBhQwN9YEIVcgIU8gYU8gEIRQLAA==",
          BinaryEncoding.Base64
        ),
        Compression.Deflate
      )
    ),
    let
      _t = ((type nullable text) meta [Serialized.Text = true])
    in
      type table [Product = _t, Date = _t]
  ),
  #"Changed Type" = Table.TransformColumnTypes(
    Source,
    {{"Product", Int64.Type}, {"Date", type date}}
  ),
  #"Grouped Rows" = Table.Group(
    #"Changed Type",
    {"Product"},
    {{"Max", each List.Max([Date]), type nullable date}}
  ),
  #"Merged Queries" = Table.NestedJoin(
    #"Changed Type",
    {"Product"},
    #"Grouped Rows",
    {"Product"},
    "Grouped Rows",
    JoinKind.LeftOuter
  ),
  #"Expanded Grouped Rows" = Table.ExpandTableColumn(
    #"Merged Queries",
    "Grouped Rows",
    {"Max"},
    {"Max"}
  )
in
  #"Expanded Grouped Rows"

Anonymous  thanks.