Um, partly correct.
You have 3 years from the last exam pass to get the CPL and the IR.
Once you have both, the exams last 7 years from the time you passed the IR or from the latest revalidation. If you keep your IR valid your ATPL passes remain valid indefinitely for upgrading to an ATPL - but only if you have a CPL/IR!
How that changes with EASA is anybodies guess, though.