Hard-set Expiration Dates allows for a specific expiration date to be assigned to subscription levels. All members in that subscription level will expire on that specific date, regardless of when their account was registered.
For example, if an expiration date of June 1 is assigned to a subscription level, all accounts registered for that subscription level will expire on June 1, regardless of when the account was created.
Once activated, expiration dates can be assigned to subscription levels from Restrict > Subscription Levels. An Expiration Date field is shown on both the Add and Edit screen for subscription levels.