Is it legal to use DO to host client's websites, and charge them for maintenance?

This may seem like a trivial question, but I’m unfamiliar with the business side of web development and don’t want to make any rookie mistakes.

I really like DO for hosting my own website, and would like to use it to host my client’s websites. Rather than instructing each client to make a DO account, and request access so I can set things up, I feel like it would make more sense to host them all under my own account.

In order to do that, however, the client’s would then need to pay me to cover the cost of the hosting (basically, clients pay me each month -> I hand that money off to DO each month). On it’s own, I think this should be fine, right?

What I’m a little more uncertain about is the maintenance part. One reason I like the idea of using DO for clients is that I would then be able to charge them for performing regular maintenance on their servers (like you do with a droplet). This would mean them giving me MORE money each month than the droplet costs. I think this makes sense on it’s own, but it feels slightly wrong to me. I don’t want it to look like I’m reselling DO’s services for more money.

So that’s where I need answers. Is the scenario I just outlined legal? Is it ethical? Is this just a bad idea, and I should have them all use their own hosting companies?

Thanks!