If you face such an issue, it is most likely related to the environment.

There are several reasons why M2E Pro tabs do not appear:

- Compilation is enabled and the source was not re-compiled after installation.

- Permissions on the Magento installation folders do not allow writing for files.

- Due to Magento User Permissions, the user cannot access M2E Pro. Make sure to provide relevant users with access to M2E Pro tabs in your Magento settings (System > Permissions > User Roles > Role Resources).

Magento 1:

Magento 2:

M2E Pro tabs are supposed to look like this in your Magento:

(Magento 1)

(Magento 2)