When used for instructional purposes, only an appropriately qualified FAA-certificated flight instructor may make any subsequent endorsements and/or pilot logbook entries. Pilot time in an ATD may be logged as instruction received, instrument time, or total time only.
Part 61
Aeronautical experience: Up to 2.5 hours in the Gleim Virtual Cockpit BATD may be credited toward your flight training if received from an authorized instructor. 14 CFR Sec. 61.109(k)(1)
Instrument Rating: Up to 10 hours in the Gleim Virtual Cockpit BATD may be credited toward your Instrument Rating. 14 CFR Sec 61.65(i)
Part 141
Private Pilot: Up to 15% of the training time required for your Private Pilot certificate may be credited in the Gleim Virtual Cockpit BATD. Appendix B to Part 141
Instrument Rating: Up to 25% of the instrument training time required for your Instrument Rating may be credited in the Gleim Virtual Cockpit BATD. Appendix C to Part 141
Instrument Currency
Instrument recent flight experience: Meet the requirements to act as pilot-in-command under IFR or weather conditions less than the minimums prescribed for VFR. 14 CFR 61.57 (c)
Fly six instrument approaches, holding procedures and tasks, and intercepting and tracking courses through the use of navigational electronic systems to maintain IFR currency.
There is no maximum amount of time that can be logged, only a maximum that can be credited toward your certificate or rating.
Refer to the FAA Letter of Authorization for the complete list of conditions and limitations.
Here is a great document with some recommendations on how to log time in a BATD.