Legal- Apartment complex question

Can anyone help with a legal question….

Is it legal for an apartment complex to limit how many times a guest can visit a week?

I don't mean how many guests at a time. I understand there's usually limits on how many people at a time.

But I mean, the same single person not being allowed to register their vehicle to park without getting towed.

Like example, I have a sibling that visits me multiple times a week. No she doesnt live with me (and I guess sometimes thats what makes these rules is to prevent people living there without paying extra rent) but she helps me with my disabled husband multiple times a week. The apartment complex asks you to register your vehicle through the towing companys website when you park in visitors parking so you wont get towed. When she tried..the company says she exceeded the amount of times she visited this week (limited to only 3 times a week) and isn't allowed to park there. And its not anything they can do, that it's the property manager that put that rule.

Do I just have to bite my tongue and suck it up or can I threaten? I couldn't really find any information online because mostly everyones questions are based on the amount of visitors and not based on the amount one single visitor can come.