IPA: /ɪnˈdʌl.dʒər/
KK: /ɪnˈdʌlʤər/
A person who allows themselves to enjoy something, often excessively or without restraint.
She is an indulger when it comes to chocolate desserts, often having more than one serving.
Indulger is formed from "in-" (meaning into or upon) and "dulge" (from Latin "dulgere", meaning to be lenient or to yield). The word refers to someone who yields to desires or allows oneself to enjoy pleasures.
Think of someone who allows themselves to enjoy or yield to their desires — 'in-' means into, and 'dulge' relates to being lenient.