Hi @Emad, congrats on shipping such a complete build. Here's a rundown with sources so you can pick the right path before upgrading. 
1. Commercial use. Yes, you can upgrade and use the app commercially. You'll just want to move off the Free plan to a paid plan (Team, Business, or Enterprise). Upgrading also gives you more AI usage.
2. Transferring ownership to your client. The cleanest way is to export the app and import it into an org that your client owns, so they become the owner of the app and its data. You can export from the app's ā¢ā¢ā¢ menu as JSON or a Toolscript ZIP, then import with "Replace app with JSON/ZIP" in their org. One important caveat: the export includes your queries, components, and modules, but not your resources (database and API connections). You'll need to recreate those resources in the client's org and confirm the queries point to them. See Import and export apps.
A great community tip for this handoff: make the last version of the app the version you want end users to see, so it displays correctly no matter which plan the client is on: Building and Shipping Apps for Clients and Ownership Options
3. Standalone / offline install. This isn't possible today. Retool apps always run inside the Retool environment, and users sign in to Retool to use them. There's no way to export the app as a fully standalone program that installs on store or warehouse computers with no Retool dependency.
4. Self-hosted deployment + plan. Self-hosting is available, but it's an Enterprise plan feature. It requires a license key (from the self-hosted portal or your account manager), and even self-hosted instances still connect to Retool for license checks, authentication, and usage reporting, so it isn't a fully offline setup either. Details here: Self-hosted requirements. Would it help if I connected you with someone on our team to talk through Enterprise pricing and self-hosting for your setup?
5. Agency program. I will look into whether the Agency program is still accepting new applications and follow up here once I find out more info.
Hope that helps you choose the right setup. Let me know if you have more questions about any of these! 