The most stable and "modern" version of Office that officially supports OS X Lion 10.7.5 Microsoft Office for Mac 2011 : Official support for Office 2011 ended on October 10, 2017 Functionality
: This version is also compatible with Lion. It lacks some of the ribbon interface improvements found in 2011 but is often easier to find at a lower price point on the used market. Avoid Office 2004 and Older microsoft office for mac os x lion 1075 updated
For a system running OS X Lion 10.7.5, your options are limited to legacy versions: Microsoft Office for Mac OS X Lion 10
Since it is a legacy product, you cannot buy it directly from the Mac App Store or Microsoft anymore. How can I get Office on my old Mac OS X Version 10.7.5 Recommendations For a system running OS X Lion 10
If the machine must remain on Lion for specific legacy software: