A "longtime customer" refers to someone who has been loyal and regular in buying products or services from a particular business over a significant period of time. Full definition
Kind of an annoying change for longtime customers who expect to be able to order online fairly reliably. (corporette.com)
You should also make an effort to show appreciation to longtime customers with special discounts and the occasional thank you when they call for assistance. (inc.com)
So now how do bookstores compete with online stores and give value that leads to longtime customer loyalty? (katetilton.com)