Hi Dhami, thanks for posting on the Community
You can upgrade your QuickBooks today to gain access to this feature. Doing so won't import previous class information, but will allow you to set these up for transactions going forward. To upgrade:
1. Sign in to QuickBooks Online as a primary or company admin.
2. Go to Settings ⚙ and select Subscriptions and billing.
3. Make sure your payment info is up to date.
4. In the QuickBooks Online section, select Upgrade your plan.
5. Review the available plans and then select Choose plan.
6. Follow the on-screen steps to upgrade your plan.
Please note, classes are only available in QuickBooks Online Plus and Advanced. To learn more on managing and creating classes in QBO, click here.