Purgatory is not about payment.
PURGatory is about being PURGED of your sin.. so yea it is payment for the "veinal" sins in your life
" Q. What is Purgatory?
A. Purgatory is the state in which those suffer for a time who die guilty of venial sins, or without having satisfied for the punishment due to their sins. "
Purgatory is one way to steal the glory from Christ and His finished work.. It makes the cross of Christ of no effect... Just as self flagellation does !