A.T. Robertson Commentary Luke 19:15

"And it came to pass, when he was come back again, having received the kingdom, that he commanded these servants, unto whom he had given the money, to be called to him, that he might know what they had gained by trading." — Luke 19:15 (ASV)

When he was come back again (εν τω επανελθειν αυτον). "On the coming back again as to him." Luke's favourite idiom of the articular infinitive after εν and with the accusative of general reference.

Had given (δεδωκε). Past perfect active indicative without augment of διδωμ.

That he might know (ινα γνο). Second aorist active subjunctive of γινοσκω. The optative would be γνοιη.