The Long Term Value ( LTV) of customers is calculated as follows: 
 
Customer lifetime value = customer value x average customer lifespan

You will need to find your Average Monthly Revenue Per Customer and know your attrition rate. After knowing both we can use the above chart to figure an average months of service, as well as take their lifetime revenue per customer / Payroll to Revenue % to get the Lifetime gross profit per customer.
 
 
Attrition Rate Per Month-

• Stats by Week shows snapshots of the customer count during each closed week. By using the total customers for the beginning of the month you are calculating attrition.
• Next, open the canceled services report (Reports>All Reports>Cancelled Services), and change the date range to the month you are calculating.
• Finally, use that total canceled divided (/) by the total customers at the beginning of the month to calculate customer attrition per month. 

 
Average Monthly Revenue Per Customer

• Using the Stats By Week, you can take the Revenue  Divided by (/) the Customer Count for a time period to get the average customer revenue.

Then by using your Payroll to Revenue %, you can take the Lifetime revenue per customer (x) payroll to revenue % to get the Lifetime Gross Profit per customer
 
For example, as seen above, I'm going to do 1 week.
 
This is all data from a sandbox so my attrition is 0% - because we didn't cancel or change any service- For this example we are going to call our attrition rate 5% for good measure meaning the expected months of service would be 20. (see above graph for Expected Months of Service)
 
The average monthly revenue per customer for me is $62,089.73  / the total number of customers 159 = $390.50
/ 
 
 
Since $390.50 is my average monthly revenue -  and my attrition is 5%, referring to the chart above  - I would expect 20 jobs from this customer and the life cycle of 20x390.50 = $7,810.
 
Now I can take my $7810 of lifetime revenue and then take away payroll -  my revenue to payroll is   so 100-52.58 - 47.42  - the lifetime gross profit per customer is - .4742 x 7810 = 3,703.502 or $3703.50 as my LTV of an average customer.