How we pay for software, and what we pay for, has changed. The old way of buying a CD with some program on it and then owning it, at least until you lost or scratched it, is out. Subscriptions are in: apparently people prefer more bills than shiny-wrapped boxes. Go figure. 

It all adds up, anyway. But not all of it has to. Sometimes, it's not even a case of paid or free - but is the big-name product actually the best?

If you're keen to save a few quid (without doing anything illegal, we stress) here are five things you have probably been asked to pay for - and whether you really have to.

1. Windows / Mac OS

Do I have to pay? Probably

You technically buy a copy of the operating system every time you buy a new computer, but if it’s pre-installed it’s a cheaper non-transferable licence that’s tied to that PC. If you build your own PC or order one made for you, you could theoretically buy a full version of Windows separately and carry that with you from computer to computer.

Or, you could install Linux for free, but that’s a whole different story. As for Mac, Apple just don’t sell computers without an operating system. 

2. Registry Cleaners or Speed up my PC apps

Do I have to pay? No

You’ve probably come across these ads telling you your computer is infested with registry errors. While that's probably true, they’re just traces of installs or uninstalls, minuscule in the scheme of things. Cleaning them up won’t speed up your PC any more than throwing out all the receipts in your wallet will make your house cleaner.

The only registry error that needs fixing by a registry cleaner is one that's pestering you - sometimes after an installation doesn't finish or you remove some malware, Windows may tell you a file is missing, prompting your 'OK' to get rid of the message. Then, use a registry cleaner - but there are free options.

3. Antivirus

Do I have to pay? No

Your PC probably came with a trial of an antivirus - which will eventually run out, leaving your precious personal files open to attack if you don't cough up the protection money.

But there are plenty of free antiviruses available that are perfectly good. Some make it hard to find the free version to download on their website, but much like rooting through couch cushions for coins, persistence pays. Here’s PC Mag’s best free antivirus list 2017.

If you're replacing an installed antivirus that came with your PC, be prepared to drag it out kicking and screaming, swearing that the free one you downloaded is a nasty virus. If you got it from a reputable site, ignore the hysterics of the ousted antivirus.

4. Winrar

Do I have to pay? No

Your 30-day trial may come to an end, but you can use this data compression tool for free forever - just click the pop-up to continue the trial every time you use it. If the nagging is too much, there are free alternatives such as 7zip, Peazip, or Hamster. These look and act a little differently, though, so unless you're a frequent file zipper, you may want to stick with familiar Winrar.

5. Office

Do I have to pay? No

Microsoft used to package Office free with its computers - today, you’re likely to get a free trial for a bit, and then be asked to pay for a subscription. (Students may be able to get it free from their institution.)

Maybe you think you need the most famous, Microsoft Office, for serious work, but you can do the same thing with free alternatives if you like. 

Microsoft's file types are most widely accepted, but can also be opened by OpenOffice and Google Docs, for instance. You may hear grumbling if you hand a colleague or lecturer a file in OpenOffice's own format or share a Docs link with a colleague or lecturer who prefers Word, but these free options do let you save in Microsoft's format too, so you can use what you like and just save as .doc, for instance.

Google Docs saving
saving a Google Doc in Microsoft Word's format

If you want to collaborate on documents, however, commenting each other's work, for instance, it's easier if you all use the same product.