A GRIN subscription has a set of limits that are set on the account based on what was agreed upon the signing of the contract. Your account limits can be found by click on the account icon in the bottom left-hand corner of the navigation bar.
If you are met with a "Ready for an upgrade?" pop-up message, then this indicates that you have reached the max capacity on one of your account limits. If you would like to discuss your upgrade options, please reach out to your Customer Success Manager.