how long does the demo version of mach3 lats before  it decides to quit. i am trying to set up my machine with it and can no longer get any sense out of it. 

The demo never expires. The only limitation with the demo is the aount of lines of code it will run ( 1000)
and the maximum speed it will run at (25,000 Pulses per second)

I think you may have other issues with your settings and it is not related to Mach been a demo.

i must have a major problem . i have not ganged any settings and it was running fine. now i have no jog . and when ii use inc jog [press and hold the shift key and the arrow for dir of x or z the motors crawl away even if i release the keys. when they stop i can make the move at 100% but if i reverse then they crawl back again befor i can make a proper jog. also i have lost the moror tuning page. i had the system running fine, even ran a couple of short files but all has stuffed up now. any ideas.

Have you tried to reinstall Mach 3 (Write down your settings).

i have reinstaled mach 3. i got my missing motor tuning  back . i have redone the back lash settings as it seemed to have something to do with this. it did much the Same\me thing, it  moves slowly on pressing a direction key, the distance is always the same . it then moves to any distance on comand but if i Change direction it crawls back stops then can be moved in jog g1. i have found if i an tick the backlash  i can be jogged and moved with no problem. then after moving it a bit i re tick the box and it moves taking up the small amount of backlash. i have checked the accuracy of the moves back and fourth with g1 and its fine. i have run a couple of small blocks repeatedly and have no probs. after homing  and setting the tool. i wont know if it will require the same to get it to run next start up. i have another problem with the g code generated in bobcad. the drawing looks fine and the post looks good but when i load it in mack3 i have the generated code it the graphic and when an arc is in i have lots blue circles mixed in. the machine tries to copy these and screws up. bit depressing. i run a full size mill with bobcad and fanuc 6m post.  i have tried the Mach3 post but get Heep's of OD ball graphics. the best i can come up with is fr fanuc 10t post.

I am not sure on the backlash issue.  But I "think" that backlash isn't supposed to work without a license.  I could be wrong on this one though.

As for the arc problem with lots of blue circles, I believe this can be fixed by changing your I J arcs from incremental to absolute, or vice versa.  Just change it from what ever it is to the opposite.  It can be found under the Config. drop down menu under State.  You will see a box for "I J Mode", just swap it and it should fix the arc/big blue circle problem right up.

Hope that helps at least a little.

this has worked some what. i itried swaping but that didn't work, but it worked when i swaped back again. thank you.