eshop update

As you have such an old version of WordPress, you will need to carry out a series of smaller manual upgrades. See Upgrading_WordPress_Extended for the full details.

Assuming you have an equally ancient copy of eShop, I cannot predict what will happen when you upgrade the plugin. All I can suggest is that you make full database backups first. You really should be keeping WordPress & all of your plugins up to date. Then you wouldn’t be in this potential mess in the fist place.