First ensure the License.xml file we emailed you is placed into the "<Gemini Root>/Apps/SimplyFi" folder.

Login as a user in the Gemini Administrators Global Group. If you have changed the "Finance Admins Group" in SimplyFi's General Admin settings, then the user you login with will need to be a member of that group.

Click on the "Finance >> Licensing" Menu item and click the reset button. SimplyFi will validate your license against the License.xml file you placed into the <Gemini Root>/Apps/SimplyFi folder.