Insurance companies guidelines differ but many do have a limit or cap on the amount of vehicles allowed on a personal insurance policy. Most insurance carriers limit the amount of vehicles on a policy to 4, but you can add more by endorsement after the insurance policy is purchased.

You can insure as many cars as you own as long as the insurance company you are working with can handle it and they do not have rules to not allow it. Most insurance providers will setup a second policy if they cannot handle the amount of cars that you own on just the one policy.

If you are using your 7 cars for business purposes it would likely be best to get business use, commercial or fleet insurance using your corporation. 

Get started with an auto insurance quote for your vehicles here.