They really ought to stop using "buy"/"purchase" metaphorically to mean something more like "one time fee for an indefinite lease that ends upon account termination." If they simply used a word better suited to the reality of the situation, then it wouldn't be a surprise that the account (which is a privilege, not a right) is a dependency of using what you paid for. Maybe something like "micro-upgrade [my account]."
Obviously eliminating that dependency is even better, but baby steps.