Yes, you will also gain back whatever was lost extremely quickly upon review.
My sense is the traits of the sub can be permanently installed as long as your acting on them
but the state the sub creates for you while it can also be recalled is more likely to diminish without use.
To have a stack/sub be permanent in traits I would say 6+ months and to have the state recall really grooved down I would say 12+ months.
For example if you run Emperor for 6 months and stop-you may not have the same insane drive, push, sense of power and dominance after taking 3 months off from it, but you will likely still have the same discipline, sense of personal standards and status, confidence.
If you run it for a year + that state will likely be your new normal.
Of course that could also fade over time or with other conditioning, so the best bet, is to run/influence yourself appropriately for whatever the most important issues/ goals are in your life.
Subs also become part of your experiences, the reference points your living while listening to them now will become the new past you remember about yourself, in the future, that will also inform your expectations and quality of life, even when no longer running that sub.