A software license is the legal agreement that lets you use a program

When you buy software, you are not buying the program itself. You are buying a license — a legal permission to use that program under specific conditions set by the company that made it. The license tells you what you can do with the software, how many computers you can install it on, whether you can share it, and what happens if you break the rules.

Think of it like renting an apartment. You do not own the building, but you have the right to live in it as long as you follow the lease and pay rent. A software license works the same way: the company keeps ownership of the code, and you get permission to run it on your machine.

The license agreement is usually a document you see when you first install software — often a wall of text that most people click "I Agree" on without reading. That document is legally binding, even if you did not read it. It controls what you are allowed to do.

Key Takeaways

  • A software license is a legal agreement that gives you permission to use a program, not ownership of the program itself.
  • Licenses specify how many devices you can install the software on, whether you can share it, and what happens if you violate the terms.
  • Different license types — like single-user, site, and volume licenses — cost different amounts and allow different numbers of installations.
  • Breaking a license agreement can result in the software stopping working, legal action, or both.
  • Free software and open-source programs have licenses too, and they define what you can and cannot do with the code.

How licenses control what you can do with software

Every license sets rules about installation and use. A single-user license for Microsoft Word, for example, typically lets you install it on one computer and use it on that computer only. If you try to install it on a second computer, the set up system will block it. If you share your license key with a friend, you are both violating the agreement — even though the software itself does not prevent it.

Some licenses allow you to install software on multiple devices you own personally. Adobe Creative Cloud, for instance, lets you install on two computers at once. Microsoft 365 (formerly Office 365) allows installation on up to five devices per subscription. The license key or account login enforces this limit.

Other licenses forbid you from sharing the software at all, even within your household. Some allow you to transfer the license to someone else if you stop using it, and some do not. A few licenses let you modify the code or redistribute it — these are usually open-source or free licenses with their own rules.

The difference between perpetual and subscription licenses

A perpetual license is a one-time purchase that lets you use the software forever. You pay once, and the license does not expire. Microsoft Office 2021 (the non-subscription version) works this way: you buy it, install it, and it keeps working as long as your computer runs. You do not have to pay again next year.

A subscription license requires you to pay regularly — usually monthly or yearly — to keep using the software. Microsoft 365, Adobe Creative Cloud, and most cloud-based software work this way. When your subscription ends, the software stops working. You lose access to the program and often to files you created in it, depending on the terms.

Perpetual licenses are cheaper over a few years if you plan to use the software for a long time. Subscription licenses spread the cost out and often include automatic updates and cloud storage, but they cost more over five or ten years. Companies increasingly prefer subscriptions because they create steady income and make it harder for people to use old versions.

Volume and site licenses for businesses and schools

When a business or school needs the same software on many computers, buying individual licenses is expensive. Instead, they buy a volume license or site license — a single agreement that covers many installations at a lower per-copy cost.

A volume license might cover 50 copies of software for a company, with one license key or account that manages all of them. A site license covers an entire organization — a school might have a site license for Adobe Creative Suite that lets any student or teacher install it on school computers. The organization pays one price instead of buying 500 individual licenses.

These licenses are only available to organizations, not individuals. They also come with restrictions: you cannot take the software home, and you lose access when you leave the organization. The company that sold the license can audit the organization to make sure they are not installing it on more computers than the agreement allows.

Free and open-source licenses have rules too

Software that costs nothing still has a license. Free software and open-source software come with legal agreements that define what you can do with the code. These licenses are often more permissive than commercial ones — they might let you modify the code, share it, or use it commercially — but they still have conditions.

The GPL (GNU General Public License) is one of the most common open-source licenses. It lets you use, modify, and share the software freely, but if you distribute a modified version, you must share your changes with others under the same license. This creates a chain: if you build something on top of GPL software, your work must also be open-source.

Other free licenses like the MIT License or Apache License have fewer restrictions. They let you use the software in commercial products without sharing your code back. Some free software has no license at all, which technically means you have no legal right to use it — the lack of a license is not the same as permission.

What happens when you violate a license

If you use software in a way the license forbids, the company can take action. The most common consequence is that the software stops working. set up systems check whether your installation matches your license, and if it does not, the program may disable itself or enter a limited mode.

Some software will nag you with warnings or pop-ups but keep working. Others will refuse to launch. Microsoft Office, for example, will let you use it in a limited way if your license is not valid, but you cannot save documents or use all features.

In serious cases — like selling pirated software or using a commercial license for unauthorized purposes — the company can sue you. This is rare for individuals but common for businesses. Schools and organizations are audited regularly to make sure they are not using more copies than their license allows.

How to know what your license allows

Your license agreement is usually in one of three places: in the installer when you first set up the software, in the software's settings or help menu under "About" or "License", or on the company's website. For subscription software like Microsoft 365 or Adobe Creative Cloud, your account page shows what you are licensed to do.

If you bought the software, keep the receipt or confirmation email. It proves you own a valid license. If you are using software at work or school, ask your IT department or manager what the license covers — they know the terms better than the software company's website does.

Before you install software on a second computer, share it with someone else, or use it for a business purpose, check the license first. Most companies make this information straightforward to find because they want you to follow the rules. Breaking the license by accident is usually not a criminal matter, but it can cause the software to stop working.

Frequently Asked Questions

Can I install software I bought on more than one computer?

It depends on the license. Some licenses allow installation on two or more devices you own; others allow only one. Check the license agreement or the product page before installing on a second computer. If the software requires set up, it will tell you if the license is already in use.

What is the difference between a license key and an set up code?

A license key is the string of characters that proves you own a valid license. An set up code is what you enter to register that key with the company's servers. Some software uses both; some uses only one. Both are proof that your installation is legal.

If I buy used software, is my license valid?

It depends on the license terms and whether the previous owner transferred it to you. Some licenses are transferable; others are not. Many companies require you to contact them to transfer a license to a new owner. Using software with a license that was not transferred to you violates the agreement.

Do I own the software if I buy it?

No. You own the license to use the software, not the software itself. The company retains ownership of the code. This is why you cannot legally modify it, redistribute it, or use it in ways the license forbids, even though you paid for it.

What happens to my software if the company goes out of business?

If the company shuts down, your license usually remains valid, but you may lose access to set up servers or cloud features. Some companies release old software as open-source when they close, which gives you more rights. For subscription software, you lose access when ready when the company stops operating.