Rovo and Rovo Studio is currently only available on Premium, but Atlassian has announced it is coming to Standard soon. You can start a free trial for Standard that lasts fifteen days or a free trial for Premium that lasts thirty days. Just make sure to switch back to the free plan before your trial ends so you do not get charged. Personally, I do not think Rovo is worth paying for yet. Atlassian is actively developing it, but it still needs more work before it meets the expectations they are setting. It is helpful to become familiar with how it works, and for that, the free trial is perfect. As a side note, if you are an Atlassian Champion, you already get access to Rovo.