To include a subject in some sort of plan or policy under old rules, terms and/or
conditions, usually because new regulations may exclude said subject. After a rule change,
new rules and regulations apply to new members (the new rules could in fact say "no new members"), unless the members were "
grandfathered in" (e.g. old, existing subjects who became members before the rule change), in which case, the old rules still apply.
Learnthespanish.com began charging a fee of $5.00 per month starting in November of last year. Members who
established accounts on their websites before then however, were
grandfathered in,
which means that they can continue to use their services for free.