I found the following (from previous replies of admins):
- Signal based on the real account available only for paid subscription. Demo signals always free.
- Demo account can subscribe to "demo" signals and to "real" signals, and real account to "real" signals.
----------------
As I understand - you want to use your demo account to subscribe (to pay for subscription) to "real" signal.
If yes so I do not know about this possibilities (because you are paying anyway ..).

- www.mql5.com
I have tried for 2 days to load a signal to my broker platform. I have just found out that the signal can only be used on a real account so I cannot
test it without using real money. Can someone explain why ?