Just to confirm HF´s point, I´ve seen airlines asking for applicants to either hold a current IR-SPA-ME or have a a multi-crew type on their licence. The implication here being that a lapsed multi-crew IR is acceptable for those with airline experience. Especially given that multi-crew IRs are renewed six-monthly.
A long time lapsed multi-crew IR might still cause problems, though, and regaining an IR-SPA-ME might help with proving currency and competence in that case.
The only definitive answer would be to talk to airlines and get their feelings on this. But as with many things to do with airline hiring, the official requirements might be different to those actually applied in the panic when a number of crew suddenly resign because Big Airlines is hiring again...
cheers!
foggy.