Since the release of Buttonizer 2.1, we have optimized Buttonizer using PHP 7 features and no longer support PHP version 5.
If you are still on PHP version 5 or lower, we recommend that you upgrade to the latest version immediately!
We will list a couple of reasons why in this article.
PHP 5 has reached it's end of life since December 31 2018. This means that it will no longer have security patches.
Websites that continue to use it could be exposed to unpatched vulnerabilities.
PHP 7 is much faster
Upgrading your PHP version to PHP 7 could improve the performance of your site as a whole!
PHP 7 could handle twice as much requests per second compared to PHP 5.
Here's an article benchmarking the speed of PHP 7:
WordPress Performance On Different Versions of PHP
How to upgrade your PHP version?
Upgrading your PHP version will differ between hosting providers.
WordPress has an article on how to upgrade your PHP version.
How to update your website’s PHP version for a faster, more secure website