Members
When a company joins, its whole team joins.
The membership belongs to the company, so everyone who works there is inside it. Whoever runs that office welcomes a colleague arriving in March, and moves a place along when somebody leaves, without anyone on your side being told. The association stops keeping a register of other people's staff, and a resignation somewhere else stops being your problem.
Let the whole company in, not one contact
The membership is the company's, not the contact's. When the person who signed it leaves, the renewal, the invoice history and the seats all stay where they are.
Let a place move on when a person does
The person who leaves keeps the record they built, and the seat returns to the pool for the next hire. Nobody rebuilds a profile because somebody changed jobs.
Show us your org structure
Most associations have one shape that breaks software. Bring yours.