Using purchased D&D 5e module in existing game

I have been running a D&D 5e game for a little while using the Lost Mine of the Phandelver adventure that I have from buying the 5e starter kit (physical copy) a while back.  I've been enjoying using the roll20 system and am thinking about buying the Phandelver module for roll20 but my biggest concern is whether I can use the resources from the module (maps, tokens, etc.) in my existing game? I'm also curious to understand all what is included in what I buy here, as it may lead to the purchasing of future adventures on roll20 if I am satisfied enough with what I get :)

If it is a module, they are design to be the base of a campaign, not an addon. With that said, it would take the use of the Transmogrifier (a pro subscription feature) to copy things from one game you created to another you created such as copy material from LMoP module to your existing campaign.

There are basically two types of adventures you can purchase on the marketplace: Modules (like Lost Mines of Phandelver) and Addons (like Tales of the Yawning Portal).  • Modules generally large collections of maps, characters, handouts and such. They can only be the basis of a new Game, so aren’t directly usable in an existing Game.  • Addons are usually smaller collections of the above, and are always added to existing Games.  As a free user, you don’t have many options for getting Module content into an existing Game. Depending on the Module, you can probably move characters from an existing Game into a Module Game using the Chatacter Vault. A Plus Subscriber can you can move Characters both directions with the Character Vault, so you could use the monsters and NPCs from the Module in your own game.  As a Pro Subscriber, you can use the Transmogrifier to move pretty much anything to anywhere. 

Ok, thanks for the info, I've thought about upgrading to a paid user for some of the features like dynamic lighting and sight lines, so I could then transfer what I need where I need to to use the module.  As far as contents of the module, what exactly comes with the LMoP module?  I would assume all of the maps do, which is what I want the most out of it, but what else comes with it?  Tokens for all of the NPCs and monsters? I can't really think of much else that could  be useful from a module like this that I don't already have in the form of the physical copy.

Everything in the physical module is in the Roll20 version. All the maps, all the monsters, NPCs, and sample characters are fully set up on the characters sheets. All monsters and NPCs are deployed to the maps edge they should be for encounters. All maps have GM later annotations as needed. All player handouts, all the Module text for the GM is loaded and cross linked. All maps have Dynamic Lighting and light sources.  It’s pretty much set up like a team of Roll20 power users spent 100+ hours putting in everything they thought someone would need to go from zero to running this module with the least effort possible on their part... which they did. =D