Native Installers for Bitnami Stacks (or VM) are completely self-contained and run independently of the rest of the software or libraries installed on your system. This means that you don't have to worry about installing any other software on your system to make the new application work and they also won't interfere with any software already installed on your system.
If you install php 7 it will not affect the Bitnami Stack (or VM) since it will use it's own PHP. If you execute
php -v indicating the full path to the php you installed it should be 7.x.
You can install your own Apache Web Server, MySQL, PHP, etc. Then you can stop all the services included in the Bitnami Stack and the migrate your SuiteCRM to your system. The benefits that you obtain from the Bitnami Stack are:
- Up-To-Date: We track every release of SuiteCRM and update our stack shortly after it's released.
- Security: If serious security issues are discovered, we provide new versions of SuiteCRM as soon as possible, often within hours of the availability of a fix.
- Consistent: With Bitnami, you get the same software stack and configuration regardless of where you are deploying SuiteCRM or other Bitnami Applications. This makes it easy to migrate between different platforms.
- Out-ot-the-box: With the Bitnami SuiteCRM Stack stack compiling, configuring and all of its dependencies are taken care of.
We recommend you to upgrade your SuiteCRM to the latest version we released which includes PHP 5.6.21, MySQL 5.6.30, Apache 2.4.20 and OpenSSL 1.0.2h. In the future, we will release SuiteCRM with PHP 7.
However, if you are very interested on using PHP 7, you can install the LAMP stack which already includes it in your VM, then install the SuiteCRM module and finally migrate your SuiteCRM as @marcos told you.
I hope this information is useful for you. If you have any other question, please do not hesitate to let us know.