Changing API



Hi, This will be a long one, please bear with me!

I hierd a web designer to make me a webpage for my company Roots & Culture.
After almost a year of waiting i requested the site back with the plugins he was using so i could finish the job my self(He had done nothing as i was given almost a blank website). He was using Visual Composer, Ultimate Addons for Visual Composer, Layer SliderWP and Revolution Slider and Stockholm Theme. We agreed that when theese needed updates he would provide me with them but switched and left me with nothing. After spending many days learning and developing my own site the VC Ultimate plugin started glitching as it needs an update. Now my question is, i need to purches the addons to make activate updates, but my WP is linked to his Envato username and API. If I were to change this would I loose all the plugins, themes and my website with it? If so, can i purches the plugins and use my license key to activate update even tho it`s not linked to my Envato User? If not, what do i do?

I do apologise for the long post, any feedback is highly appreciated!!

Thanks in advance