My Office 365 package is about to expire. Can I instal LibreOffice alongside it?
Yes, that is possible. LibreOffice can work with files in Microsoft Office 365 format, which have filemame extensions like .docx. But best is to work in the native format of LibreOffice, which is “ODF extended”.
You should convert your files before Microsoft Office 365 expires. You can import a file with .docx filename extension in LibreOffice, when you first start LibreOffice and then use “Open File” at the top left of the starting screen. A double-click will not work, because the filename extension is still associated to Office 365. When the file has opened, then use menu File > Save As and save it in .odt format. Sometimes you get better converting results, when you start Microsoft Office 365 and open the .docx file there, and then use its “save as” and save to .odt format. Therefore you should not wait till it actually expires, but convert the files immediately.