You may want to charge someone a monthly fee while their membership is on hold, here is how to do that.
Create a new plan template. Call it 'Hold Fee' etc
Set parameters and cost as it suits. but make sure to set 'Allow Check-ins' to NO.
When a member asks to put their membership on hold, pause that membership then manually add this 'Hold Fee' plan to them. Just remember to cancel this hold fee plan when they resume the membership back up.