What about two licenses, such as 'subscriber' and 'commercial', with different charges for each.

The subscriber license would have access the binary files and any source that would generally be included (such as the custom indicators that are included in the product now).

The commercial license would provide access to the source code of the application (via private GIT), along with unlimited (internal) use rights.

There would be no functional difference between the compiled application.  From a charging perspective you can continue down the path of a once-off (or annual fee) for the subscriber license, and a monthly (or annual) fee for the commercial license.

My guess is that the majority of retail traders are not also C# developers so would have no use for the commercial license anyway.

Your current source code license would probably not need to change too much in this case.

If you wanted to provide access to the source to your contributors, you would be able to issue them with a 'commercial' license allowing for multiple system internal use and the source code.

Hello Popov

I have a completely different  idea about pricing of your software , 1st we have to know which market segment you will target  , if you will target the MT4 platform traders whom need to automate  strategies using FST so my idea is to make the FSB pro free and only price FST Pro  , why FST pro free will be more profitable , Because

1- it will increase the base of your testers '' testers will separate to 2 groups 1st group whom are serious traders and will buy the FST pro if they find the FSB pro is an effective profit generator , others whom like testing and playing with softwares  and those will try to search for cracked version as you mentioned B4 and this second group not a candidates to be buyers in future ''   and protecting FST Pro in my opinion will be more effective against cracking more than the FSB Pro because it have two parts which have to be linked properly to work fine also traders will not risk they live accounts with craked versions which may collapse any time

2- making FSB pro free will make lots of programmers adapt your software the programmers will work as a third party making indicators of their own to sell in the market  and this will lead to more buyers to FST pro
and increase its popularity , and this rout will need from you as i asked before to build a big manual demonstrate deeply programming indicators using C#and/or FSB language also this will need you to allow other ways than hard coding to be linked with the FSB pro , i mean dll .