The AddIn is available as xll files. These are files that have an xll extension and include the Excel AddOn software.
There are two methods to install the AddIns to Excel.
Temporary for the current Excel session only
Permanent in which the AddIn remains installed and ready on this session and future sessions
Temporary - with the temporary method, you double click the AddIn file. Excel will then start up and present you with a dialog. If you say Ok, the AddIn will be available for the current Excel session. When you then close and then reopen Excel, the AddIn is not loaded automatically. If you need to use the AddIn, you would need to start Excel by double clicking each time. This method is convenient while testing new AddIns.
After double clicking the xll file, this dialog will appear. Cilck “Enable this add-in for this session only.”
Permanent - with the permanent method, when you open Excel, the AddIn is automatically available for usage by existing sheets and new ones.
There is no need to double click the AddIn at the start of each session.