FCL.720.A (d) 3 MPTR requirements, requires ATPL, no mention of validity.
FCL.915.FI (b) (2) (a) for FI, exams last forever
Sorry to sound pedantic
rudestuff, but I have to question your interpretation of Part-FCL - a PPL with no IR and without an ATPL issued cannot retain ATPL credits indefinitely. You are correct that neither FCL.720 or FCL.915 mention validity periods and certainly a PPL with ATPL TK credits could undertake an FI course in 20 years from now but would not maintain the original ATPL credits unless they held an IR and had renewed it at least every 7 years. Same for a Type Rating - the intention of Part-FCL is that the credits are valid at the time of course commencement.