The creator of a Game determines the benefits that game has. If you upgrade to Pro, Games you create will have Dynamic Lighting, API support, custom character sheets, etc. Players joining your games will have the benefits of those things. If you join someone else's game, your having a Pro subscription won't affect what benefits you receive in that game. Marketplace purchased compendiums (Player's handbook, Zolo's Guide, etc) can be shared with a limited number of games (5 at a time) containing a limited number of players (5 for free accounts, 10 for Plus, 15 for Pro. (not counting you) ). You can choose which of your games you are sharing your compendium collection with. With marketplace purchases of images and modules, you'll have direct access to those things for games you create, and can bring elements of them to games you join (for example character tokens are brought along with the character when you move them between games with the Character Vault).
