There are some cases when JChem for Excel closes unexpectedly. After Excel is closed the following dialog appears:
If you press No, JChem for Excel operates further normally after launching it again.
If you press Yes, the JChemExcel.Functions add-in gets disabled, and the JChem tab doesn't appear in Excel. To enable it again please follow these steps:
Select the jchemexcel.functions from the list and press Enable.
Launch Excel again, JChem for Excel will work properly, the JChem tab will appear correctly in Excel.
If you are interested in tutorials for most important features of JChem for Excel and Office, please check our Youtube Playlist.