Query ref validity date of ATPL's - 7 year IR renewal limit

[Stobart]

Hi Folks,

I have not renewed my IR in 5+ years

I know that there is a limit of 7 years before ATPL exams expire.

Can an instructor or flight examiner confirm the following. The 7 year expiry date is it based on the expiry date of the last IR or the actual test date of the last IR.

Thank you for your help.
Stobart