How to update composer in PHP

Question

I'm new to the composer I'm using a plugin here they used composer. I getting some errors that the reason I want to update composer because might be an issue with the composer i'm not sure what is the issue here. my question is in my plugin composer is already installed. Are there any other things I have to install in local?

How should I update this composer used in the plugin?

I'm using this plugin https://github.com/codehaiku/envato-purchase-code-verifier

here I just download the plugin and added my token and API but when I was entered purchase code I was getting an error Invalid Purchase Code . Can anyone suggest me is there any other alternative way to this instead of using this plugin some other plugins?

Any help will be appreciated.

Answer 1

To answer your question as asked:

composer self-update

However, if you're worried that the composer file could be bad download a new version here

If you pay attention to the steps you'll eventually be at one where there's a file called composer.phar in the directory you ran it (probably in your webroot/public_html folder) and then you can be sure you're using the new version by using the command

php composer.phar update

that will update your libraries.

On a potentially more helpful note, contact the vendor as your key may, legitimately, be wrong and/or you purchase an invalid code from a 3rd party.