Bug fixes for general core bugs in 3.5.x ended May 2019 (12 months).
Bug fixes for security issues in 3.5.x will end 10 May 2021 (36 months).
minimum PHP 7.0.0 Note: minimum PHP version has increased since Moodle 3.3. PHP 7.1.x and 7.2.x are supported too. PHP 7.x could have some engine limitations.
