Active Customers by month - Time to Drop out

[FelipeDBA]

Hi all, i'm struggling with a requested measure and i don't know how to achieve it.
Measure requested: Amount Active Customers by month
Description:

Suppose a customer buys 60 units of a product in Jan/2019 and uses 1 unit a day. Knowing this, this customer will come back to my store only when his product ends, something near mar/2019. In my measure, I want to show the number of customers actives by month and this one, although haven't bought in feb/2019 I need to count him as active, because I know he doesn't need to come back every month but it is a active customer. 

Regards,

[v-chuncz-msft · Accepted solution]

@FelipeDBA ,

You may add a calculated column [end date] and refer to the post below.

https://community.powerbi.com/t5/Desktop/Accumulate-sum-minus-abandoned/m-p/206947#M91174