grandfathering 

To allow a subject to continue to function under an old rule, plan or policy, even after changes to that rule, plan or policy has been made. The change to the rule, plan or policy may include the abolishment of the rule, plan or policy itself.

DuJour Cellular is phasing out the ABC cell phone plan soon, but they're grandfathering members with existing ABC plan subscriptions. Grandfathered ABC plan subscribers can continue to use their old plans, but new subscriptions will not be allowed.

grandfathering by Tatertoot July 27, 2016

grandfathering 

Keeping a plan for your cellphone even though they don't offer it anymore.

Verizon doesn't have unlimited data anymore, but since I got my phone when they did, I'm grandfathering it.

grandfathering by dralexxx September 18, 2013