Just wanted to chime in here that the Blesta version 3-series (e.g. v3.6.0) will never support php 7+. It simply can not. There are backward incompatible changes introduced in php 7 that prevents Blesta v3.6 from being runnable on that version of php.
In order for Blesta to support php 7+, Blesta must be updated to resolve those backward incompatible php 7 changes, and in so doing has to introduce backward incompatible changes in itself. This means that in order to support php 7, an update to Blesta requires a major software release (i.e. moving from version 3.x to version 4 following semantic versioning standards). This is precisely what we did do by releasing Blesta v4.0, and with that version you can run php 5.4+ or php 7+ using the provided ioncube-encoded files for php 5, php 7, or php7.1+ respectively.
Ioncube itself does not support php 7+ with its php 5 encoded files, so that's why different encoded files must be used for your particular php version.