@jmolina,
Before diving into the DAX, I created a simple star schema data model with lookup tables for clubs and members:
Without the proper model and relationships in place, even getting basic DAX measures to work is difficult. Once I set that up, I created the following measure to count the number of unique clubs visited by each member:
# Clubs Visited =
CALCULATE(
COUNTROWS(
VALUES( 'Sales Data'[Club Code] )
),
FILTER(
'Sales Data',
[Visited] = 1
),
VALUES( 'Members'[Member Code] )
)
I then created a second measure using CONCATENATEX() to list the specific, unique clubs visited by each member:
Clubs Visited List =
CALCULATE(
CONCATENATEX(
VALUES('Sales Data'[Club Code]),
'Sales Data'[Club Code],
", ",
'Sales Data'[Club Code],
ASC
),
FILTER(
'Sales Data',
[Visited] = 1
),
VALUES( 'Members'[Member Code] )
)
Here’s the resulting table:

I hope this is helpful.
Full solution file posted below.
PS: If you have any questions about setting up a proper data model, I strongly recommend going through this course: