Pay with Ether

On Ethereum mainnet, Polygon, Arbitrum, or Optimism

Because of taxes, paying with crypto can be done only six months or more.

Can I pay monthly?

As described above, transacting with crypto is more expensive as a business. If you want to pay monthly, you can with a card.

Can I pay with an ERC-20 or another blockchain?

Yes, earnifi supports payments of WETH on Polygon. Earnifi also supports payments of ETH on Optimism or Arbitrum!
Both have a gas fee of nearly zero!