Yes. It keeps them because nothing in your scenario removes them.

You didn't mention any abilities removing counters, so the only possible thing that could be removing counters are the rules.

There are only three instances when counters are removed from objects by the rules, and none of them are relevant to the current situation.

1. Dealing damage to a Planeswalker removes loyalty counters.
2. SBAs cancel out +1/+1 and -1/-1 counter pairs by removing them.
3. SBAs remove extra counters when a permanent has a limit to how many of a given kind of counters it can have.

That's it. Counters are never removed from objects except in those circumstances or by abilities that instruct you to move or remove them^[1].

Under normal circumstances, a counter are never removed from the object on which it is paced; it just ceases to exist when the object ceases to exist.

121.2. Counters on an object are not retained if that object moves from one zone to another. The counters are not “removed”; they simply cease to exist. See rule 400.7.

1. This includes three keyword abilities that remove counters:

   • Fading (fade counter)
   • Suspend (time counter)
   • Vanishing (time counter)

Yes. It keeps them because nothing in your scenario removes them.

You didn't mention any abilities removing counters, so the only possible thing that could be removing counters are the rules.

There are only three instances when counters are removed from objects by the rules, and none of them are relevant to the current situation.

1. Dealing damage to a Planeswalker removes loyalty counters.
2. SBAs cancel out +1/+1 and -1/-1 counter pairs by removing them.
3. SBAs remove extra counters when a permanent has a limit to how many of a given kind of counters it can have.

That's it. Counters are never removed from objects except in those circumstances or by abilities that instruct you to move or remove them^[1].

Under normal circumstances, a counter are never removed from the object on which it is paced; it stays on the object until the object ceases to exist (at which point they cease to exist too).

121.2. Counters on an object are not retained if that object moves from one zone to another. The counters are not “removed”; they simply cease to exist. See rule 400.7.

1. This includes three keyword abilities that remove counters:

   • Fading (fade counter)
   • Suspend (time counter)
   • Vanishing (time counter)