The Love you earn doesn't fade here on Sessions! Any Love you receive, both from Fan donations or from Bonus Love added by us, will stay in your account without any kind of fading, cuts, or depreciation.
At the moment, there's no limit on the amount of Love you can have in your account - you can keep the Love over there in order to make larger Cash-outs in the future, or you can ask for a Cash-out at any given week where you're an Artist Level 4 or above.