Show aggregation from left table but only for values appear on lookup table

[smpa01]

My sample source data is following (pbix attached) - https://drive.google.com/file/d/1PXMUglwo2VElWUOcvr8wEWpBgGoA0meG/view?usp=sharing

|                key                      |
|-------|---------|-------|---------------|
| site  | service | month | key           |
| site1 | serv1   | 1     | site1-serv1-1 |
| site1 | serv1   | 2     | site1-serv1-2 |
| site1 | serv1   | 3     | site1-serv1-3 |
| site1 | serv1   | 4     | site1-serv1-4 |
| site1 | serv1   | 5     | site1-serv1-5 |
| site2 | serv1   | 1     | site2-serv1-1 |
| site2 | serv1   | 2     | site2-serv1-2 |
| site2 | serv1   | 3     | site2-serv1-3 |
| site2 | serv1   | 4     | site2-serv1-4 |
| site3 | serv1   | 1     | site3-serv1-1 |
| site3 | serv1   | 2     | site3-serv1-2 |
| site3 | serv1   | 3     | site3-serv1-3 |
| site3 | serv1   | 4     | site3-serv1-4 |
| site3 | serv1   | 5     | site3-serv1-5 |
| site3 | serv1   | 6     | site3-serv1-6 |
| site3 | serv1   | 7     | site3-serv1-7 |
| site4 | serv1   | 1     | site4-serv1-1 |
| site4 | serv1   | 2     | site4-serv1-2 |
| site4 | serv1   | 3     | site4-serv1-3 |
| site4 | serv1   | 4     | site4-serv1-4 |

| Lookup |
|--------|
| site   |
| site1  |
| site3  |
| site4  |

I am building a matrix viz by bringing site,service,month from key tbl and counting how many total months are there by each site-service but I only want to show the  aggregation for sites that only appear in Lookup.

My measures are following and this is what I get after dropping the measure which I don't want.

countSiteService:=
CALCULATE ( COUNT ( 'key'[month] ), REMOVEFILTERS ( 'key'[month] ) )

countSiteServiceLookup =
CALCULATE (
    [countSiteService],
    TREATAS ( VALUES ( Lookup[site] ), 'key'[site] )
)

My desired result is following

|            Result                |
|--------|---------|-------|-------|
| site   | service | month | Count |
| site1  | serv1   | 1     | 5     |
| site1  | serv1   | 2     | 5     |
| site1  | serv1   | 3     | 5     |
| site1  | serv1   | 4     | 5     |
| site1  | serv1   | 5     | 5     |
| site3  | serv1   | 1     | 7     |
| site3  | serv1   | 2     | 7     |
| site3  | serv1   | 3     | 7     |
| site3  | serv1   | 4     | 7     |
| site3  | serv1   | 5     | 7     |
| site3  | serv1   | 6     | 7     |
| site3  | serv1   | 7     | 7     |
| site4  | serv1   | 1     | 4     |
| site4  | serv1   | 2     | 4     |
| site4  | serv1   | 3     | 4     |
| site4  | serv1   | 4     | 4     |

Thank you in advance.

  @AlexisOlson 

[smpa01 · Accepted solution]

Resolved here, credit to @AlexisOlson 

https://stackoverflow.com/questions/69194893/dax-to-aggregate-only-for-values-from-lookup-table/6919...

[amitchandak]

@smpa01 , Try like

countSiteServiceLookup =
CALCULATE (
[countSiteService],
filter('Key', 'key'[site] in values(Lookup[site] ))
)

[smpa01]

It does not keep the previouly created count by partition @amitchandak 

[smpa01]

I can do this, but it does not give me correct total count in the subtotal level

countSiteService = 
VAR _lookupSite = CALCULATE(max(Lookup[site]),CROSSFILTER('key'[site],Lookup[site],Both))
VAR _res = CALCULATE ( COUNT ( 'key'[month] ), REMOVEFILTERS('key'[month]),'key'[site]=_lookupSite)
RETURN _res