Your payment methods will likely be frozen after a period of time. If you have credit on these services then when the credit runs out it will try to bill the card you have on file and it will likely fail.
If you need to keep things running, designate people to take over your SaaS business if that is what you are referring to. If you mean personal accounts on SaaS providers, they will likely be closed unless that service recognize the concept of "transfer upon death" which some financial services do. Ask each of the vendors if they have this service. If you meant a company that you run, consult with a lawyer to determine how your company can be transferred upon your death. This is usually a process involved in the creation of a business to satisfy investment security.