ExpressionEngine 3 has entered the first phase of its EOL, that of becoming a legacy product. A legacy product is no longer developed actively, but still receives critical security patches and is eligible for support for one year. This means that ExpressionEngine 3 will be retired on December 14, 2018. You can read more about our EOL policy for legacy software in the Support FAQ.
If you upgrade a version 3 license to ExpressionEngine 4, you will still have access to the v3 download, in case critical patches are released before you make the jump to v4.
Thus, we have just released ExpressionEngine 3.5.13, the final “normal” patch release for version 3. It includes a small handful of bug fixes and adds PHP 7.2 compatibility. You can find details in the ExpressionEngine 3 change log.