Does a Window 10 license allow using it as a Web server?

On Windows 10 Pro, the number of connected devices is limited to 20. The Windows 10 license states:

Device connections. You may allow up to 20 other devices to access the software installed on the licensed device for the purpose of using the following software features: file services, print services, Internet information services, and Internet connection sharing and telephony services on the licensed device.

This limitation will severely limit concurrent users on your website, though the limitation language is actually to limit to people or devices, regardless of concurrency.

I'd also recommend carefully considering if you want to host SQL Server on the same box as your website.

• SQL Server is licensed by the CPU core. (CAL licensing generally doesn't make sense for websites because you have to license every random user to connect from the internet.) SQL Server Standard Edition is licensed at $1,859 per core, with a 4 core minimum. You must license every core on the server. Usually you want to have every CPU cycle available to SQL Server. Having your website chew up expensive CPU cycles is expensive.
• If you're storing any passwords or personally identifiable data, the security of running SQL Server on a machine exposed to the internet is a security risk that increases the risk your website and data will get pwned.

You cannot legally use Windows 10 to serve public websites with IIS/SQL server due to the 20 device limit. Please also note that the limit is not for concurrent connections but for the named devices (similar to per device CALs for server OSes).

You also mentioned that the VM is going to be run at the remote datacenter. You are not allowed to run a retail copy of Windows 10 in a virtual environment, you'll need to purchase a Windows 10 VDI license which is significantly more expensive.

Given the constraints, your best option will be a combination of Windows Server Standard and SQL Server Standard configured for Web Workloads (which I previously mis-labelled as Windows Web Server). Web Workloads allows you to run a web server software (IIS), database server (MS SQL) to support the web server frontend, and DNS service to assist the two but nothing else. This usage does not require any CALs so you only need to license the basic operating system and SQL server, which is a reasonable cost (especially since you already seem to have SQL Standard license).

Disclaimer: Even though I am pretty familiar with Microsoft licensing due to having to deal with it on more-or-less monthly basis, my advice should not be taken as final and I expressly disclaim any responsibility for any licensing errors and any losses arising from it. Please consult your Microsoft licensing partner. MS licensing is hella confusing.