I suppose “LEM” means “Lay Eucharistic Minister”?
That’s exactly the problem.
They are not ministers, they are extraordinary ministers, and they are only extraordinary ministers when they are actively engaged in assisting the priest by distributing Holy Communion.
Unless they are in a situation where some priest has actually appointed them at that moment to distribute Communion, then they are not ministers of any kind, they are only potential extraordinary ministers.
They should not be presenting themselves as “LEMs” any more than your average parish priest should have business cards printed that read “Father John Doe, Confirmation Minister” based on the fact that a priest can be an extraordinary minister of confirmation under certain circumstances.
Extraordinary Ministers of Holy Communion do not hold any office in the Church, they have no title, nor should they give themselves any title that implies an office.
§ 3. The non-ordained faithful may be generically designated “extraordinary ministers” when deputed by competent authority to discharge, solely by way of supply, those offices mentioned in Canon 230, § 3(56) and in Canons 943 and 1112. Naturally, the concrete term may be applied to those to whom functions are canonically entrusted e.g. catechists, acolytes, lectors etc.
Temporary deputation for liturgical purposes — mentioned in Canon 230, § 2 —
does not confer any special or permanent title on the non-ordained faithful.(57)
vatican.va/roman_curia/congregations/cclergy/documents/rc_con_interdic_doc_15081997_en.html
That’s pretty clear. Extraordinary Ministers of Holy Communion (potential ones, at that) do not have any title, nor should they.
Appending the letters “LEM” after their names is directly contrary to the Church’s discipline.