Can I upgrade from Standard Version to Enterprise Version?

Yes, you can upgrade from the Standard Version to Enterprise Version by signing in to your Navicat Customer Centre (https://customer.navicat.com/), find the product(s) you want to upgrade, and then simply hit the Upgrade to Enterprise button located next to the product you wish to upgrade for. You can also find the upgrade fee on the next page, after you select next from the previous steps.