That depends on which version of the Education Software you purchased:
- LEGO® MINDSTORMS® Education EV3 Software Single User
As the name implies, this is only allowed to be installed on a single computer: "The single license version of the EV3 Software allows you to install and run the software on one computer." - LEGO® MINDSTORMS® Education EV3 Software Site Licence
This version allows you to install the software on a number of computers within a single location: "The site license version of the EV3 Software is necessary when installing on more than one computer. It allows you to install and run the software on all computers located at the address of the purchasing institution."
If you're planning on installing this on more than three computers the Site License is the way to go.
Note that the Home Edition is a separate download, and would have it's own licensing, but appears to be freely available, and installable on as many computers as you like - details of some of the differences can be found in this answerdetails of some of the differences can be found in this answer to "What is different between the EV3 Home and Educational sets?".
In response to Alex's comment:
Without seeing the full wording of the license, it's hard to advise you correctly, however:
- Usually you can reinstall software on the same computer after an OS reinstall - depending on the validation mechanism you may need to contact Customer Services to get it reset, but I doubt this will be the case with this.
- Again, this is typically supported by most software licenses - it's often things like transferring ownership that are expressly excluded.
