We currently are running version 2.5.2. Our webhost had upgraded to php7.0 and we are at php 5.6.40. How do we upgrade to newer version of EE that includes php7.0. Will there be compatability issues with our current version with EE updates?
You need to first upgrade to EE3, and then upgrade to the latest version. This is covered in the docs:
Packet Tide owns and develops ExpressionEngine. © Packet Tide, All Rights Reserved.