docs: update all documentation for subscription auth, billing tiers, and API key management

packages/opencode-plugin/README.md

@@ -8,6 +8,8 @@ OpenCode plugin for AgentLens — trace your coding agent's decisions, tool call
 ## Requirements
 
 - OpenCode >= 1.1.0
+- An AgentLens account -- register at [agentlens.vectry.tech/register](https://agentlens.vectry.tech/register)
+- An API key created in **Settings > API Keys** in the AgentLens dashboard
 
 ## Install
 
@@ -44,7 +46,7 @@ Add the plugin to your OpenCode configuration at `~/.config/opencode/opencode.js
 }
 ```
 
-Set your API key:
+Set your API key (create one at **Settings > API Keys** in the [AgentLens dashboard](https://agentlens.vectry.tech)):
 
 ```bash
 export AGENTLENS_API_KEY="your-api-key"
@@ -52,6 +54,8 @@ export AGENTLENS_API_KEY="your-api-key"
 
 The plugin activates automatically when OpenCode starts. No code changes required.
 
+Each OpenCode session counts as one trace (one session) for billing purposes. See the [billing documentation](https://agentlens.vectry.tech/docs/authentication-billing) for plan details.
+
 ## What Gets Captured
 
 The plugin hooks into OpenCode's event system and records: