Hi.
It looks like a pond snail to me too. As long as the snails aren't too big (I have seen some big ones with 2-2.5 cm long shells) and your axolotls are big enough/adults, it should be ok. However, even though the shell is pretty fragile, it's still a shell, and it could be a choking/impaction hazard.
If it were up to me, I wouldn't purposely introduce them to my tank, however if they were accidentally introduced, I would probably leave them be if they weren't causing problems.
I am curious whether you intend to put some in.
Post what you decide and if anything happened.
Good luck