Thank you for your continued patronage.

Literal

Every-time honorable-patronage [for-に] thank-you.

毎度ご贔屓にありがとうございます is a standard business greeting — heard at shops, restaurants, and service counters. ご贔屓 (ごひいき, 'patronage/favor') uses the honorific ご prefix. The entire phrase is a fixed keigo expression.