I'm sure many of us have experienced something like this.
My observation would be that if you want to continue enjoying relations with her, it would be wise to reciprocate her generosity with some of your own. She'll have been acutely aware of the clock running over, and the risk represented by barebacking and despite being undoubtedly fond of you, she'll also have been weighing up how much of a fool she's been, and in corollary, how much an exploiter you've been, and whether as a result, she ought to bar or ghost you.
An extravagant but sincere gesture of freely-given goodwill on your part; a huge tip, an expensive or tasteful present and/or a beautiful meal together will likely go a long way to mollifying those thoughts, and lay the groundwork for more of the same closeness. The real trick, imv, is to do this with no expectation of later bonuses. If given in that spirit, and in proportion to her offerings to you, (ie: if you've had 5 hours free time from her, make your gesture of appreciation
at least the same, and possibly greater value), and you'll very likely find that the benefits continue to flow.
It could be that you merely want to bank the freebies given and declare yourself a lucky winner. But Tempest is quite right here, when he says...
enjoy it while you can - it doesn't last forever. One day they'll change their number and you'll never hear from them again.
In my view, a situation like the one you describe is a treasure that you ought to be able to relish looking back on in years ahead. If you want to keep it going, you're going to have to put out in equal measure yourself.
After all that, I've just read the OP's follow-up meeting. And WTF folly of youth is this?
'Nonetheless we sit and eat and scroll on our phones for a bit' 
I Used to put it on the bedside table and she never counted in front of me at least...
They
always count it, and take note.
