Update from OS X Lion 10.7.5 to macOS Mojave 10.14
Refer to this macOS upgrade instructions webpage, (currently it refers to macOS Mojave):


macOS - How to Upgrade



  Upgrading from OS X Snow Leopard or Lion
  
  If you’re running Snow Leopard (10.6.8) or Lion (10.7) and your Mac supports macOS Mojave, you will need to upgrade to El Capitan (10.11) first. Click here for instructions.