I accept Bitcoin and Ethereum for consulting work, but would like some feedback for Service Type Agreements that span upwards of a 1-year in an enterprise setting. What's the best method for approaching set coin prices in a legal service agreement where the markets can fluctuate?
If you want to go all in on cryptocurrency, you can make an agreement stating the payment method as BTC or ETH and then the amount. The value of these currencies may vary with time and hence no one really signs such an agreement, yet.
The best you can do is sign an agreement stating the USD value of your services payable in equivalent Bitcoin or Ethereum considering the conversion rate at the time of payment (excluding the transaction fee!) for every payment processed.