You must have your MT4 running all the time to receive signals. You either must leave you computer
on or get a VPS (virtual private server: like another computer online).
If anyone wants a good priced VPS to run multiple MT4 and EA's on and receive signals, here is one I have been using for years. Only $10 a month.
To get it go here: Interserver . Scroll down to VPS.
Choose Windows. 1 slice is $10. I run up to ten MT4 platforms and EA's on one slice.
They have been around for decades. I have been with them for 5 years with no problems