I researched this a bit previously for proton and I think there was one case where someone had their account deleted but they were using the service excessively. I also read that if you do upgrade to a premium subscription support can help you merge your accounts together so I guess they kind of support it. If your making a few accounts even on the same IP you are probably fine just don’t login to them in quick succession and you will probably be fine. I do suggest you use an aliasing service when you can.