The steps will differ depending on the method you’ve used to install your M2E Pro. Please find your option in the article.
After Magento Team made the announcement about Magento Connect closure, the website was...
Sometimes Magento Connect Manager does not show update even if it is available.
If you were locked out of the admin panel with an error after you've installed the new version through the Magento Connect, most probably, you have a Compilation option enabled in your Magento.
Check out the Module upgrade options.
There are several reasons why M2E Pro tabs do not appear after installation.
Check the reasons why synchronization may not run after the Module upgrade.
The M2E Pro menu may disappear after the upgrade because of the following reasons: