Hi Dan,
Sorry for the delay in responding! There shouldn't be any kind of limit on the number of installs, so that error is peculiar. It is more likely some kind of problem with the license file itself rather than your account. Would you mind emailing me with the exact error text (a screen shot should be fine) so I can help diagnose better?
To expedite the process i'll have you email my personal email: mcheli@ptc.com
Please let me know if you have any questions!