We supply services on a rental basis.  These are invoiced and paid for in advance with the regular invoices being raised on the 1st of month 1 for the services to be delivered in month 2. 

We memorise invoices and have them set to reoccur monthly.  On each invoice we have an S3 line which we have the rental period in i.e.. "Service rental for June 2016". 

Is there a method of auto-populating this field (or another line) with this information.

1 idea would be a function that says something along the lines of if the invoice date on this invoice is in month 1 then the detail in this field should read "Service rental for Month 2 year x"

Thanks in advance.