Macintosh owners can upgrade their computers to OS X Lion by running the OS X 10.7 installer from a download or physical disk, if their computer meets the minimum system requirements. A download code for the OS X 10.7 installer is available through the Apple store website.
The minimum system requirements for upgrading OS X to Lion are a Macintosh computer with at least 7 gigabytes of free hard drive space and 2 gigabytes of RAM. The computer must have an Intel Core 2 Duo, i3, i5, i7 or Xeon processor and must be running OS X Snow Leopard, version 10.6.6. Apple recommends users upgrade to 10.6.8 before upgrading to Lion. It is necessary to upgrade computers running versions of OS X older than Snow Leopard to upgrade to at least 10.6.6 before updating to Lion.
OS X Lion is no longer the most current version of the OS X operating system as of May 2015, as OS X version 10.10 has superseded it. Many computers that can upgrade to Lion are also able to upgrade to Yosemite directly. However, there may be problems with compatibility with specific types of Macintosh computers or programs that can still make upgrading to Lion rather than Yosemite desirable. For example, some older Mac Pro models are incompatible with OS X 10.8 or later, but can still upgrade to Lion.