The upgrade tool doesn't contain any checks and Microsoft says it will remain available until further notice.
For the general public, the free upgrade offer for Windows 10 ends on July 29. However, if you use assistive technologies, you can still get the free upgrade offer even after the general public deadline expires as Microsoft continues our efforts to improve the Windows 10 experience for people who use these technologies.By the way, the Windows 10 Anniversary Update will be rolled out tomorrow (August 2nd).