The Blinovitch Limitation Effect limiter, or BLEL, was a Time Lord device that limited the effects of the Blinovitch Limitation Effect, making it safer for one to meet their earlier selves. Its use also meant that memories could be retained of past encounters.
Drax's third incarnation teamed up with his later ten incarnations in order to con the Fourth Doctor into stealing the limiter, which was what allowed them to cooperate on this scheme in the first place.
This scheme involved the twelfth incarnation taking it back in time to where the third incarnation was, since the third hadn't stolen the limiter yet and frame the Doctor into stealing it under the pretence of stealing files that incriminated Galdron Cabot, secretly another incarnation of Drax, as a gangster.
The plan was for the Twelfth to hand the older version of the limiter to the Third Drax, take the earlier version of the same device and use it for a few centuries until the twelfth incarnation gave it back to the Third Drax, who got the Fourth Doctor to put it back minutes after it was stolen by him in the first place. In between these two points, the limiter would be used for multiple crimes involving several of Drax's incarnations since it had been acquired years before when he was in his third incarnation. (AUDIO: The Trouble with Drax)