Formula to flag missed periods

Hello,
I am working on an idea I have to automate expense accruals. I have a data grid that shows all of the vendor history. One of the columns is periods/months. I want to test on this column to flag when an accrual is needed. example. I have a landscaping vendor. The history shows in the period column that we have paid them months 1 through 8. If we are in period 10 I want the flag that an accrual is needed. So the tool would know we are in period 10 and it would see that we have made 8 consecutive payments and are missing 2. Same concept where the history shows we pay someone quarterly. search the periods and see that we have paid a vendor for 2 quarters and need to accrue for the third quarter.

here is an example of the file. the period field is column M