I have several LLC accounts and want to know if there's a plan that I can add all LLCs under one Quickbooks or do I need separate accounts for each LLC?

One QBO account is for one company file. You should consider using QB Desktop Pro or Premier to manage multi company files with a single license.

 It's a great idea to have your queries posted here with us, patandyo. I can provide insights to help you manage your QuickBooks accounts and subscriptions.

I agree with 4Gal's information, QuickBooks Online account must be compatible with one company file. There isn't a subscription available that can add all LLCs under one QuickBooks data. You need to have a separate account for each LLC.

If you wish to manage your QBO subscription, you can update and view your plans to keep track of your billing history. I'm leaving this guide for additional reference: Manage billing, payment, and subscription info in QuickBooks Online.

In case you want to track the income, expenses, or profitability by business segment of your file, you can use  the class tracking feature to get specific reporting needs and your segment's financial health.

I'll always be available in this forum for any additional questions when managing your company files. Just keep me posted, so I can get you covered. Keep safe!